Sony rushes from one flagship phone to the next, making only iterative changes most of the time. With the Z5 generation, there are three different variants of the phone—a standard Z5, the Z5 Compact, and our focus today, the Z5 Premium. What makes it premium? Well, it's the first phone with a 4K display. Does that really do you any good, though? Let's find out.

Specs Display 5.5-inch 3840x2160 LCD, 806 ppi Processor Qualcomm Snapdragon 810 RAM 3GB Camera 23MP rear facing, 5.1MP front facing Storage 32GB with MicroSD slot Measurements 154.4 x 76.0 x 7.8 mm, 180g Battery 3430mAh (non-removable) OS Android 5.1.1 Price $670-720

The Good Fingerprint reader The fingerprint reader is a nice thing to have, and putting it in the power button is smart. Battery life Two solid days of moderate use. Seven hours of screen time in a single heavy day is possible. Build quality Water-resistant design with metal frame. The USB port doesn't need a flap like older phones. Camera The camera takes nice photos in good lighting conditions. The oversampling and zoom tricks are rad. The shutter button is a nice touch too. Display It's the first 4K phone, if that's important to you.

The Not So Good Display again Almost never runs at 4K resolution. Causes streaming apps to max out at 1080p. Snapdragon 810 It gets warm and throttles, but not as badly as some other phones. Buttons The volume rocker is too low on the body of the phone to be used comfortably. Design Sony's phones all have this same boring rectangle shape. The glossy glass back panel isn't as nice as the frosted glass on the other Z5 phones. Camera again The low-light performance is bad due to noise and a weird blue-ish haze. Fingerprint reader again Recognition isn't as good as some others and registering prints takes pretty long. Price and availability Not for sale in many regions, and it costs around $700.

Design

At the risk of sounding like a broken record, the story here is much the same as it was in our recent Z5 and Z5 Compact reviews. Sony's phones look a certain way, and the Z5 Premium is no exception. It's an unremarkable rectangle with slightly rounded edges and water-resistant chassis. The back panel is glass, but it's not frosted like the Z5 and Z5C. Instead, it's still the glossy kind that picks up fingerprints like mad. It also looks cheaper than the frosted glass backs, in my opinion. That's odd for a phone marketed as "premium." The edges of the phone are aluminum, but they're extremely high-gloss to the point that they almost look and feel like plastic.

The Z5 Premium is a hefty device at 180g. That's more than phones like the Note 5 with a slightly larger display. I will concede that Sony has nailed the art of distributing weight inside a phone. Something like the OnePlus 2 feels strangely heavy because the weight distribution is off, but the Z5P is more comfortable thanks to its even distribution. Sony calls this "Omnibalance." Marketing terms aside, the Z5P is doesn't feel too heavy, but there's nothing particularly ergonomic about the sharp edges and flat back.

On the left edge is a flap that houses the SIM card and microSD card. Older Sony phones also packed the USB port in there, but thankfully those days are over. Sony has now managed to get the microUSB port on the bottom of the phone without a port cover, yet still maintain the water-resistance. The flap on the side also feels much more study than it did in past years.

On the right edge is where things get interesting. You've got a power button with built-in fingerprint reader (which I'll get into later), a camera button, and a volume rocker. I felt like the power button was placed far too low on the tiny Z5 Compact, but it's about right on the Z5 Premium. They're both at about the midpoint of the phone, but it makes more sense in the case of the Premium. It's completely recessed, though, and tactility could be better.

The volume rocker is perhaps even more ludicrous than it was on the Z5 Compact. Just like on that phone, the volume rocker is placed below the power button—way below. This is a tall phone, and the volume rocker is two-thirds of the way toward the bottom. There is absolutely no way to comfortably change the volume while using the phone with one hand. The camera button is at the very bottom, but I sort of get that. It's in the right spot to work as a shutter button while holding the phone in landscape. The button itself is two-stage and has a soft enough tactile bump that it won't shake the phone when you take a snapshot.

There are some rather substantial bezels above and below the display, but the phone does have stereo speakers. They sound fine, above average for a phone even. They seem somewhat more tinny than the Nexus 6P or Moto X Pure to my ear. They do get quite loud without excessive distortion, though.

Display And Battery Life

This is the big question, isn't it? Can you make a phone with a 5,5-inch 4K screen without destroying battery life? Well, yes and no. The Xperia Z5 Premium has pretty solid battery life, but it's not always acting like a 4K phone. Confused? Let me explain.

The Z5P is the world's first 4K smartphone. There's no disputing that from a hardware perspective. This phone has a 3840X2160 LCD, which works out to a whopping 806 pixels per inch. That's a few hundred more than phones like the Galaxy S6 and Nexus 6P with their 1440p displays. It gets plenty bright for use outdoors and viewing angles are about as good as they can be. Colors look accurate to me as well. It doesn't have that AMOLED pop, but that's what you get with an LCD.

Here's the problem—well, one of the problems—running a phone at that resolution would murder the battery. Sony's solution is to render the UI at 1080p and just display that on the 4K screen. Seems like kind of a waste, doesn't it? This isn't entirely Sony's fault, though. Android Lollipop does not support native 4K display resolution at all, so right out of the gate some trickery was needed.

So, most of the time when using the Z5 Premium, you're looking at a 1080p image that has been scaled to fit on a larger resolution screen. This saves a huge amount of power on the GPU side, allowing the Z5P to get solid battery life. I was actually surprised at how well the Z5P does while illuminating all those pixels (note: it probably still uses more power than a 1080p screen). I'm seeing about two days of moderate usage. You can hit 6-7 hours of screen-on time with this phone if you try. It's a cut above phones like the GS6 when it comes to longevity. That's with the UI always at 1080p, though.

There's only one way you can get native 4K resolution to activate on the Z5 Premium: watch some 4K video. The way you do this is weird (and kind of stupid). You can't just fire up YouTube and watch 4K video content. In fact, you can't even watch 1440p video. Sony is running the UI at 1080p, so the YouTube app (and most streaming apps) will be limited to that resolution. A phone like the LG G4 or Galaxy S6 can stream 1440p YouTube video just fine because they run at native 1440p resolution. Sony says it upscales 1080p video (pixel-doubles), but that's just a hack. If you want to actually see 4K on your 4K screen, you have to shoot your own on the phone or sideload 4K video that you get from other sources. How does Sony, a company with ample video properties, not think to include even a little 4K video to show off the display?

At any rate, watching native 4K video on the Z5 Premium is really neat. It looks great, but I don't know that I could tell the difference in a blind test with 1440p video running at native resolution. Your ability to take advantage of the higher resolution of this screen will depend greatly on how good your eyes are. For most people, I think having a 1440p screen running at native resolution is a preferable situation.

Fingerprint Sensor

Sony has opted to include a fingerprint sensor in the Z5 series devices because that's just the thing to do these days. It's built into the power button, which again, is on the right side of the device. This is generally a great location for the sensor. It's convenient to press with at least one finger of either hand and allows you to wake up and unlock the device with one press.

When the sensor works, it's a nice feature to have. However, I think the accuracy leaves something to be desired. It's not as good as the Nexus 6P or Galaxy S6, for example. Sometimes I'll have to lift and remove my finger two or three times to get it to detect the fingerprint correctly. The Z5P sensor also seems to have trouble with detecting prints when you tap the button from an odd angle. The Nexus 6p by comparison, is able to recognize your fingerprint no matter how you set it down. When the Z5P's sensor does work (which it does most of the time), the detection and unlock happen very fast. Registering new prints is slow, though. It takes 15-20 presses.

This phone runs Lollipop, so the fingerprint reader is not using the official Android APIs. That means it won't count as a secure unlock method for Google services. Whenever this device does make it to Marshmallow, maybe the accuracy of the sensor will improve. We can only hope. Don't get me wrong, it's better to have this feature than not. I just wish it was a little more accurate.

Camera

The Z5 Premium uses the same 23MP Exmor RS image sensor you'll find in both of the other Z5 variants. So, as you might expect, they all have a lot in common. You can check the Z5 and Z5 Compact reviews for more detail on this sensor. From what I've seen with the Z5 Premium, I'm really not sure how this phone has gotten so much praise for camera quality. It's just not as good as some of the competition.

Before we get into specifics, you ought to know that despite having a 23MP image sensor, the Z5 Premium (like the other Z5s) actually just takes 8MP images with oversampling. You can crank up the resolution to 23MP, but that seems to make the camera app a little sluggish and the results aren't noticeably better in any way except for fine details on stationary objects. I'd even say the exposure is noticeably worse in this mode. The upshot of the oversampling mode is that you can digitally zoom without losing pixels, which is pretty cool.

Just like the other Z5 devices, this phone takes nice photos in bright light. Detail is good and colors are accurate. I feel like capture speed is a little slower than I'd like, which can lead to some blurring, but this has improved a bit with recent updates to Sony's camera software. Performance is much worse when light gets less than ideal. In average indoor settings, the Z5 Premium still spits out good pictures, although the ISO starts ramping up. You'll probably see a bit more noise in dark areas than a phone like the Galaxy S6 or LG G4 might produce.

In poor lighting is where the camera falls apart. Android cameras have come a long way in the last few years. The best among them can now take a photo in a dimly lit room that's usable, but I don't think that's the case with the Z5 Premium. The ISO shoots up pretty quickly, meaning lots of noise and graininess. I'm seeing ISO values of around 2000 on some photos that aren't even that poorly lit. There's also an odd blue haze in some photos, which I didn't see on the Z5 Compact. I can't rule out a defective sensor on this phone, but I suspect this is just a software processing issue. It only shows up in dim settings.

It's also worth noting that the Z5 Premium doesn't have optical image stabilization, a serious omission in my book. The software equivalent does a good enough job, but you can tell it's not as robust as true optical stabilization. Sony's camera app also makes it hard to access some common features like HDR mode, which can only be toggled on when in manual mode. I don't really trust the auto mode to select the right scene all the time either. It seems fond of switching to document mode when there's something white in the frame.

I'm disappointed in the performance of this camera, perhaps even a little more than I was with the Z5 Compact. It's not worse per se, though the shutter lag is a bit more noticeable. The issue is that this is supposed to be a "premium" phone, and the camera experience isn't as good as you get with a lot of other flagship devices. Sony dropped the ball.

Software And Performance

The Z5 Premium ships with Android 5.1 like the other Z5 variants, and with the exception of the wonky 4K screen stuff, it's identical to the other ones. We've gone over Sony's software a few times, so I won't go into extreme detail, but there are a few broad strokes to note.

Sony's Android skin is lighter than something like TouchWiz, but it still suffers from the problem of simply making changes for the sake of making them. For example, the home screen is a custom Sony launcher, but there's no reason for it to exist. It does nothing special. The app drawer allows different sorting modes and you can change the icon size. That's all. The process of adding icons to the home screen is actually slower and more awkward than other launchers as well. Sony should have just slapped the Google Now Launcher on this phone and called it a day.

The Small Apps framework is present on the Z5 Premium, and it's slightly more usable on the 5.5-inch screen than it is on the comparatively tiny Z5 Compact. Small Apps are basically floating windowed apps, but only a few of them exist. There's a calculator, browser, and a few more. Some are little more than glorified widgets, though. Look, there's nothing wrong with having this feature, but is anyone getting any value from using it on a phone? I imagine not.

It's nice that themes exist on the Xperia phones, but I feel like they're underutilized. Sony's default theme has some odd color choices, like the blue status bar, and most of the included ones make only minor changes. There are a few more available for download, but it's not going to improve the experience much. Oh, and the navigation buttons. I will never understand why Sony's home button needs to he noticeably larger than the multitasking button.

My review unit is an international device, so the selection of apps it comes with might be very different than what you see on an eventual North American model, assuming that ever happens. Sony likes to bundle a ton of its own services. You've got PSN, Xperia Lounge, Play Memories, and so on. Most of it can be disabled or uninstalled, so it's not a huge deal. Sony's gallery and music player are actually rather nice. I like them more than what you get from the likes of Samsung or LG, that's for sure.

Sony's keyboard is actually surprisingly competent as well. It's grown on me as I've used the device. I like that there are a few different skins built-in, all of which look nice. The gesture input is accurate, as are the word suggestions. And I can't praise Sony enough for using the stock Android emoji. They are a million times better than the crap that Samsung and LG design. Sony squanders most of that good will by not including in-line spell check, though. Misspelled words are not underlined for easy correction. You can either have spelling autocorrected (maybe) or go without spell checking at all. Samsung does the same thing, and I really don't get it.

Performance on the Z5 Premium has been very good overall. It's powered by a Snapdragon 810 SoC, which has been a problem in the past. The 810 runs hot and can throttle down aggressively in some devices. It seems to vary a lot from one OEM to the next. For instance, the Nexus 6P seems fine with the 810, but the HTC One M9 was a little furnace that had to shut down cores to manage heat. The Z5 Premium is somewhere in between. When this phone gets warm, it ends up about as fast as the Snapdragon 808, which has two fewer high-power CU cores. So, it gets hot and throttles down, but the 1080p rendering probably saves it from a worse fate.

Conclusion

You're looking at about $700 to get your hands on this phone, and that's not even for a North American version with proper warranty support. I'm not sure what Sony's plans are for the Z5 series going forward, but it would be nice to at least have the option of buying one here. As for whether or not you should, that's a more complicated question.

From a technical standpoint, having a 4K display in a phone is really neat. Practically, it really doesn't matter. I'm not even talking about the questionable benefit of having that many pixels, there's just very little use for 4K on this phone. Almost everything is rendered at 1080p, so no streaming video services will even output video at higher resolution than that. Sony didn't include any 4K video content, which is the only time the screen runs in native 4K. It's nice that you can watch the 4K videos you capture in native resolution... I guess. The screen is mostly marketing hype.

The nice thing about the display shenanigans is that the Xperia Z5 Premium gets great battery life. I have no problem hitting two full days and you can probably hit seven hours of screen time in a single day if you use it heavily. Note, if you're actually watching 4K video, that'll drop precipitously.

The camera is disappointing, though. I'm not sure what Sony's issue is with photo processing and sensor tuning lately, but it's behind the likes of Samsung and LG. I know that some sites have loved the Z5 series cameras, but I'm just not seeing impressive results. In bright light things are good, but indoors the images get noticeably grainy.

The case for this phone is harder to make than the one for the Z5 Compact. That device is the only small phone with flagship specs, but there are plenty of alternatives to the Z5 Premium. At $700, I have a hard time recommending this phone when there are cheaper devices with better cameras and screens that can actually run at native resolution. It's not a bad phone, but it's not worth the asking price.

Note: our Z5 Premium review unit was provided by Expansys.