Hardware: phone

Let's start off with the main specs. The PadFone 2 is powered by Qualcomm's latest and greatest Snapdragon S4 Pro APQ8064, a 28nm, 1.5GHz quad-core SoC based on the Krait architecture (which outperforms Cortex-A9 in many ways). This makes ASUS the second third manufacturer to offer APQ8064 on a phone, right after the LG Optimus G (which we reviewed recently) and the Pantech Vega R3; and it's to be followed by the Xiaomi Phone 2 in China and the HTC J Butterfly in Japan. The graphics are driven by the almighty Adreno 320, and like many recent flagship phones, there's 2GB of RAM stacked on top to keep the gears well-oiled. As for the cameras, what used to be an f/2.2, 8-megapixel main camera is now boosted to a 13-megapixel Sony BSI sensor plus f/2.4, five-element optics. Meanwhile the front-facing imager has gone from 0.3 megapixels to 1.2 megapixels. As usual, we shall take a look at camera performance later on.

Buyers do get a generous 50GB of free ASUS WebStorage service for two years.

In Taiwan, the new PadFone is offered in flavors of 16GB, 32GB and 64GB, whereas in Europe it'll only have 32GB and 64GB options. Unlike its predecessor, however, there's sadly no microSD expansion. Users craving for more storage space will have to get their fix via USB OTG or the cloud. Buyers do get a generous 50GB of free ASUS WebStorage service for two years, which is no doubt to help push the ASUS Open Cloud Computing initiative, but more on that in the software part of this review.

Cellular connectivity comes from Qualcomm's MDM9215m radio which supports GSM/EDGE/UMTS/DC-HSPA+/LTE -- compatibility of which will depend on the specific regional variant: worldwide, North America (two versions), Japan, Australia and China. This particular review is based on the worldwide model which supports GSM 850/900/1800/1900, WCDMA 900/2100 and LTE 800/1800/2600. However, since there's no LTE network in Taiwan (ironically), we could only use 3G for the majority of the time during our review -- we did sneak back to Hong Kong very briefly and managed to hook the phone onto the LTE networks there. We were happy with performance on both ends of phone calls, even in noisy environments thanks to the ambient noise reduction technology. Other radios include the usual 802.11a/b/g/n, Bluetooth 4.0, NFC, FM radio, GPS and GLONASS.

From afar, the PadFone 2 could be easily be mistaken for its predecessor that sported the same design language. But put the two together and you'll easily spot the larger, sharper and brighter 4.7-inch, 720p, 550-nit Super IPS+ LCD. We should point out that the new display is so bright that even on the dimmest setting, it still blinded us when we were in total darkness. You know, bedtime browsing. Hopefully this isn't a fixed setting so that ASUS can tweak it. Our One X (AT&T) has a similarly impressive viewing angle and gapless display feature, though the PadFone 2 appears to have a more accurate white balance -- the former's culprit being its warmer artificial tone. Some may miss the overly vibrant colors on the original Padfone's Super AMOLED, but in general, LCD's still king when it comes to accuracy, pixel density and outdoor performance.

When switched off, the front side of the phone is dominated by the black screen plus a tapered, glossy plastic lip along the bottom, only to be interrupted by the little shiny silver earpiece near the top. But when switched on, you'll see the three capacitive soft keys light up between the screen and the logo at the bottom. We prefer these to the old virtual keys for the sake of screen real estate, and better yet, you can set the keys' backlight duration to two seconds, 10 seconds or forever.

All of these are surrounded by a rigid aluminum frame that's garnished with a few buttons like before. This time, the power button's been shifted from the top side to the right, just above the volume rocker, which was two separate buttons on the first PadFone. And the spot where the power button used to be -- next to the 3.5mm headphone jack -- is now occupied by a seemingly trending pin-push type micro-SIM tray (a triangular paper clip is included), which is a big change from the old mini-SIM slot underneath the removable battery on the original PadFone.

You'll never get fingerprints on the back of the phone, and the texture feels good, too.

Also changed on the frame are the micro-HDMI port, micro-USB port and contact points for the external antenna (inside the PadFone Station). These are now combined into one 13-pin MHL socket customized by ASUS and located at the bottom of the phone, thus leaving the left of the aluminum frame squeaky clean. The PadFone 2 does come with a 13-pin connector USB cable. Fortunately, you can still use the regular 5-pin MHL plug or micro-USB plug for power and data, but the latter can be a bit loose, and the former won't be able to handle video -- you'll need to get an optional MHL-to-HDMI adapter from ASUS. We doubt this would be too much of a problem for most users, anyway.

Moving on to the backside of the phone, apart from the darker shade of gray, the polycarbonate back cover is very much the same as before. It features an etched ripple pattern surrounding the 13-megapixel camera, thus simulating the cool visual effect of circular-brushed metal as seen on the Zenbooks and the aluminum Transformer Pads. This also means you'll never get fingerprints on the back of the phone, and the texture feels good, too.

The lack of microSD slot is certainly a disappointment.

ASUS admits that the PadFone 2's back cover isn't designed to be removed on a regular basis, in order to minimize the amount of dust and fluff getting in as well as to protect the delicate NFC antenna -- a feature that was missing on the original PadFone. We found it much harder to rip off the new cover, but once it's out of the way, you can see the 3.8V, 2,140mAh lithium polymer cell (instead of the old 3.7V, 1,520mAh lithium ion cell) which is sealed by a big label that screams "Please DON'T remove the battery." Sadly, there's no microSD slot to be seen. So in this case, the removable cover is solely for the convenience of maintenance. We're fine with the semi-fixed battery given that we can use either the tablet or a USB battery pack to juice up the phone, but the lack of a microSD slot is certainly a disappointment, especially for those who have already splashed out on 32GB or even 64GB cards. We'd like to think that adding microSD expansion back in would not have had a huge impact on the phone's thickness.

Last but not least, there's the loudspeaker on the back which is about twice as large as the one on the first PadFone, so as you'd expect, it gets a lot louder. ASUS also claims that this is 40 percent larger than what the other leading smartphones use. With great power comes great responsibility, so the engineers at ASUS' Golden Ear Team have added in a few lines of code to minimize distortion and mechanical interference under high amplitude -- this is apparent when you blast out music at maximum volume (especially with Music Mode enabled in the AudioWizard app, but more on that later). Naturally, this small speaker still lacks in bass, but there's always the bigger one on the PadFone Station.

Hardware: tablet

With the PadFone 2 inserted, the combo is still lighter than the new iPad alone.

You might have already seen us raving about the new PadFone Station in our earlier hands-on, but let's recap: this module is essentially a 10.1-inch, 1,280 x 800 external IPS LCD display for the PadFone 2, but at the same time it also serves as a 3.8V, 5,000mAh (19Wh) battery pack. That's slightly smaller than the 24.4Wh battery in the first PadFone Station, but remember, the PadFone 2 itself now has a bigger battery. Together they add up to about 27Wh, which isn't too far off from the old 30Wh combination. Besides, what's more important is the weight reduction that ASUS has managed to achieve for the slimmer PadFone Station: from a hefty 724g down to just 514g. That's a 30 percent reduction! In other words, with the 135g PadFone 2 inserted, the combo is still lighter than the new iPad alone (652g). By contrast, the original PadFone and its PadFone Station together weighed more than the first iPad, which made it very difficult for ASUS to sell its "N+1" concept.

The smaller battery, the removal of the battery LED indicator and the new 13-pin MHL connector at the bottom (but, for some reason, upside-down compared to PadFone 2's) certainly helped achieve the lighter weight. Still, we've been told that the engineers also looked at every component to see how they could shave off a tiny bit of body fat wherever possible. The biggest contributors to the weight reduction are probably the obscure Corning Fit Glass (on both the phone and the tablet), the magnesium-aluminum alloy frame and the cover-less docking method. Interestingly, ASUS has been working on the new docking mechanism for a year and a half, which confirms our theory that at some point the two PadFones were developed alongside each other. We recall that back when we interviewed Michelle Hsiao from ASUS Design Center, there were PadFone Station mockups that featured straightforward slide-in docking methods, but Hsiao said at the time they didn't have a way to ensure secure docking for the exposed phone, hence the bulkier solution in the end.

So how does the new docking mechanism work? Well, there's the new 13-pin MHL connector, of course (so the old PadFone obviously won't fit), but that alone wouldn't be enough to keep the phone tucked securely inside the bay. And by secure we mean strong enough to withstand powerful shakes. This is where the cunning part comes in: instead of throwing in a typical slide-lock mechanism, ASUS has devised a system that pushes four toothed, rubber pads -- of the same material used by bicycle brake pads -- against the two long sides of the phone when inserted. You should feel a light click once the phone hits the bottom of the bay, and it usually takes about one second -- instead of two on the original PadFone Station -- for the tablet interface to load up.

The phone managed to stay inside the bay while this author was shaking the upside-down tablet as hard as he could.

As you'll see in our walkthrough video, the phone managed to stay inside the bay while this author was shaking the upside-down tablet as hard as he could (please don't try this at home). And then it gets more intriguing when you realize how easy it is to insert and remove the phone -- it's as if the locking mechanism only comes to life when you shake the device. We'd rip the tablet open to find out what kind of black magic this is, but until we get hold of our own retail unit, ASUS' patent-pending secret is safe. However, at some point later we tried the shake test again and the phone did eventually slip out, and we think it's something to do with the dust or some sort of powder that managed to get onto the rubber pads, so be careful.

There's not much else visible on the new PadFone Station apart from the 1-megapixel webcam at the usual location, as well as the power button and the volume rocker around the top-left corner -- neither of which have been prone to accidental clicks for us. If we have to be nitpicky, our only gripe is that the phone isn't flush with most of the tablet's backside, meaning when placed flat on the table, the slate may wobble if you tap on either side too hard -- we're thinking of scenarios like typing or playing certain games. Hopefully the dedicated PadFone 2 Station sleeve will solve this problem. While using it, we were able to hold the new PadFone Station up for much longer thanks to the combination of rounded edges, soft-touch texture and, most importantly, lighter weight; but when walking around, we do prefer to grip the slate by the top side, with the top of the phone in our palm. We just need to remember to clean the lens every time before using the camera.

What's left to talk about here is the slate's mono loudspeaker, which is apparently 32 percent larger than what other tablet makers use. To our surprise, even with the tighter space inside the new PadFone Station, the speaker still manages to output loud music with surprisingly adequate warmth and crisp treble for its size, but you do need to use the AudioWizard app (enabled by default) to achieve this performance. For those seeking something closer to audiophilic quality, there's always the good old wired headphones (and AudioWizard is disabled when headphones are plugged in). Even the bundled stereo headset sounds way better than what most other phones get -- it's identical to the one that came with the original PadFone, but that does also mean the microphone is still way too far from the user's mouth, so we always end up having to hold the mic up to talk. It's rather odd that ASUS is still using this cable arrangement.

Hopefully ASUS will eventually admit defeat and come up with a matching hinged keyboard dock.

So, what about a keyboard battery dock? Despite reports that "confirmed" a dedicated keyboard dock is in the works, ASUS burst our bubbles by telling us that this is simply not true. We are worried -- sure, you can always just get a Bluetooth keyboard or even plug in a USB keyboard via an OTG dongle, but that's not quite as glamorous as being able to fold everything into a netbook form factor -- which we could with the original PadFone, despite the total weight of 1.49kg. Hopefully ASUS will eventually admit defeat and come up with a matching hinged keyboard dock, because that would add so much more emphasis on using Android for productivity.

Some people were expecting to see a PadFone Infinity, in the sense that the 10.1-inch tablet module would come with a 1080p panel. We asked ASUS whether it would consider releasing such an update any time soon, but the response was that while it's possible to output 1080p from either the phone or the tablet, the manufacturer intentionally chose to keep similar resolutions across the two displays for the sake of easier app and video rescaling, thus saving processing power and battery life. In other words, the time's not right; or maybe ASUS is just putting on a poker face.

Software

Much like the original PadFone, its successor delivers a near-vanilla Ice Cream Sandwich experience that's slick in both phone and tablet modes; and we're certain that the same will apply to the upcoming Jelly Bean update. The only interface customization you'll find here are the thumbnail overview of up to seven home screens (pinch anywhere on any home screen to toggle), as well as the "Pad Only" tab in the app drawer, the handy ASUS Quick Setting panel in the notification tray, and "ASUS customized setting" in system settings. For those who don't know, the "Pad Only" area simply houses apps that are tagged as pad-only by users -- you can do so by tapping and holding an app icon in the drawer, followed by dragging it to the "Add Pad-only Tag" button in the top-right corner.

The ASUS Quick Setting Panel hasn't really changed much since the latest update on the original PadFone. Situated above the main native notification panel, the extra panel has a screen brightness slider sandwiched between the outdoor mode button and automatic brightness button. Above those is a sliding row of quick toggles (albeit in a slightly different order than last time): WiFi, Mobile Data, Smart Saving, Instant Dictionary (which is new), WiFi Hotspot, Bluetooth, GPS, Vibrate and Auto-rotate Screen. One small request for ASUS' developers: it'd be nice if users could rearrange these toggles, as we can with Xiaomi's MIUI as well as LG's UI 3.0 (on Optimus G, Optimus LTE II and others). The next row up in the panel contains three buttons that take you to the advanced menus for WiFi, AudioWizard and system settings. Strangely, in tablet mode said WiFi button is replaced by a dual-battery indicator, but it shouldn't be too hard to add the former back into that row for the sake of consistency.

We still don't understand why the original Android notification panel can't be as intuitive as ASUS' implementation. Google's version requires one more tap to toggle the secondary panel for the common settings, including screen brightness, WiFi, auto screen rotation toggle and airplane mode. On the other hand, ASUS knows how to do it right: give users instant access to all the main settings after just one tap. Google could learn a thing or two from its Taiwanese buddy.

After multiple mentions, now might be a good opportunity for us to properly introduce AudioWizard: it's essentially an audio-tuning app developed in collaboration with Waves, an award-winning audio DSP solutions company. Think of it as what Beats Electronics is to HTC, albeit with less branding power. There are five presets here: music mode, movie mode, recording mode, gaming mode and speech mode. Oh, and there's an "off" button which apparently saves a little bit of power. While the app works in both phone mode and tablet mode (but disabled when headphones are inserted), we've been told that it's tuned specifically for the PadFone Station's loudspeaker, but nonetheless, the improvement is apparent: audio is both louder and livelier with added warmth. Needless to say, this enhancement can only go so far, so don't expect the PadFone Station to replace your high-end speakers any time soon.

SuperNote on PadFone 2 is now at version 3.0 and supports multilingual handwriting recognition.

Like its previous Android products, ASUS has thrown in its usual bundle of apps: App Backup, App Locker, File Manager, Mirror, MyDesktop (powered by Splashtop Remote), MyLibrary, MyNet (DLNA), Polaris Office 4.0, SuperNote, Watch Calendar and WebStorage. It's worth noting that SuperNote on PadFone 2 is now at version 3.0 and supports multilingual handwriting recognition (which worked well for us), WebStorage cloud syncing and PDF export. And while we're at it, ASUS' WebStorage also offers instant photo uploads, Microsoft Office Web Apps integration (so you can edit Office documents online using the official interface) and file collaboration. It's sort of ASUS' own take on Google Drive and Microsoft SkyDrive. As for widgets, you get the same old battery indicator, task manager and PadFone Station Assistant (for setting the charging mode and how incoming calls are handled), along with both the old version and a new version of the ASUS weather widget. If you prefer the previous weather widget then fret not, it's still available on the list.

Naturally, there are some new apps on the PadFone 2: ASUS Studio, Instant Dictionary and MyBitCast. ASUS Studio is simply a beefed-up version of Gallery, as it lets you view photos and videos by folders, time, location (on top of Google Maps) or album tags, not to mention the magazine-like layout as well. It also comes with the identical set of basic editing tools like cropping, auto-fix, effects and levels. As this is the default viewer for the camera app, users will familiarize very quickly. Our only feedback for ASUS here is that the locations of some of the photos were a bit off (for instance, this author was never on the north bank in the above map), which is weird considering the sky was clear at the time, plus there weren't many tall buildings. If this is merely a software issue, it'll definitely be fixed.

The Instant Dictionary is even more exciting: toggling it in the ASUS Quick Setting panel will bring up a small round button that snaps to either the left or right side of the screen. Once you click it, you can then swipe your finger across any text area to look up definition or translation, and you can choose your desired target language in the app's settings. It even does offline single-word translation between Chinese (Simplified), Chinese (Traditional), English, French, German, Italian, Korean, Portuguese, Russian and Spanish. While popular apps like Flipboard, Pulse and Zinio are supported, there are also many that got left out -- not even Chrome and Twitter as of the 9.8.8.32 firmware -- so the button didn't always show up. Another issue is that a lot of times, we'd miss one character or accidentally highlight a nearby punctuation mark, which makes the translation a tad slower as it needs to talk to the server. We're certain that it's only a matter of time before ASUS issues a fix through an OTA update.

Finally, MyBitCast is similar to SuperNote but with more emphasis on audio notes, photos and videos. Strangely, users will need to have a WebStorage account in order to use this simple app, whereas SuperNote works as a standalone app just fine. But either way, you get the idea, and this seems like a potentially useful tool for the likes of students and journalists. For those interested, we compared the sound recording performance between the original PadFone, its successor and the HTC One X at a low rooftop in Taipei City:

ASUS PadFone 2:

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ASUS PadFone:

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HTC One X (AT&T):

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From what we can hear, the One X has excellent noise suppression, but that also became a double-edged sword as we moved to about two meters away from the phone -- the aggressive suppression started to interfere with our voice and therefore made it hard to interpret the distant speech. The original PadFone sounded the most natural, but this meant that much noise was also captured throughout. Luckily, the PadFone 2's voice recording performance is somewhere in between the two aforementioned devices: some noise is suppressed, and what's left is clean enough for speech interpretation. It goes without saying that your results may vary depending on the environment and your audio source.

Obviously, all of these apps work in both phone mode and tablet mode. If you're familiar with the original PadFone then you would have already come across Dynamic Display, a name coined by ASUS that describes the technology behind the transition between the two interface modes. We've already mentioned that said transition has been sped up from two seconds to just one, but better yet, ASUS claims it's also done some work to ensure that the UK's top 100 apps work correctly with Dynamic Display.

We still love showing off how a video clip continues to play after the Dynamic Display switch.

Still, for some weird reason, only a portion of the bundled apps have Dynamic Display switch enabled by default, so users will need to go into "ASUS customized setting" in system settings to choose more apps. Even Google's Gmail, Play Store and Play Music apps need to be enabled manually, so we have a feeling this is more of a policy issue rather than a technical issue -- Play Store and Play Music certainly worked fine for us over Dynamic Display, just not Gmail. Likewise, we still love showing off how a video clip continues to play after the switch, though due to the lack of DivX certification, native video playback is limited to MPEG4/H.264/H.263/WMV at 1080p. That said, there are other apps that can handle some AVI and MKV files -- we use MX Player most of the time, and it's almost fully compatible with the Dynamic Display switch.

In terms of performance optimization, ASUS has kept the three levels of settings but presents them in a different manner. By default, the Smart Saving mode is enabled on the PadFone 2, which has a set of predefined conditions for certain scenarios. For example, cellular data connection is cut when the phone is sleeping and the screen brightness is fixed to 60 percent while reading books, watching videos and listening to music. You can also see the full list and edit each scenario in system settings. Obviously, the mileage varies depending on your usage behavior, but the options are there should you require them. As for the performance freaks, you can enable Ultimate mode which is right at the bottom of the "ASUS customized setting" menu, but we didn't notice any performance gain during our benchmark tests. This means much like the original PadFone, the CPU can already go full throttle when needed even under "Normal" mode, whereas under Ultimate mode the phone would stay at top performance most of the time.