Hardware

Last year's iPhone 5 reveal was a showy affair meant to highlight Apple's new industrial design and taller screen (if you recall, the company went so far as to raise the phone onto a pedestal, accompanied by a generous helping of sparkling lights). There was no spectacle made of the 5s this year, since the flagship looks virtually the same as its predecessor. Basically, if you fell in love with the iPhone 5's aluminum chassis and chamfered edges, you're in for more of the same here. (Time will tell if this also means that the 5s is just as susceptible to dings and scratches as the iPhone 5; Apple tells us this year's selection of colors are more "metallic," and that will help them wear better. We'll see.)

Unless you're a hardcore Apple fan who's taken the time to memorize all the minor differences separating the iPhone 5 and 5s, you're likely to mistake the two at first glance. Not only is every button and port in the same place, but the phone's measurements remain unchanged as well: at 123.8 x 58.6 x 7.6mm (4.87 x 2.31 x 0.3 inches). It even weighs the same, at 112g (3.95 ounces). Likewise, the 5s also features a 4-inch, 1,136 x 640 Retina display with a pixel density of 326 pixels per inch, a brightness rating of 500 nits and an 800:1 contrast ratio. Again, more of the same. Clearly, Apple's still satisfied with the resolution and screen size, though we wonder if the company will have a change of heart with next year's flagship.

As you're probably well aware, the 5s is to the iPhone 5 as the 4s was to the iPhone 4 (and as the 3GS was to the 3G). All told, this is the third time in Apple's seven-year smartphone history that it's carried over the iPhone's design into a second consecutive year. Even so, the design isn't identical. Of all the enhancements made to the 5s, the most notable has to be the new Touch ID fingerprint scanner, which is embedded directly into the home button. Look closely and you'll also notice a dual-LED flash on the back, as well as the word "iPhone" in a slightly lighter font near the bottom of the rear to match the look of iOS 7. Under the hood, the 5s steps up from Apple's A6 chip to the A7, the first smartphone processor with 64-bit support. Additionally, it claims to double the iPhone 5's CPU and GPU performance, thanks in part to a new coprocessor called the M7, which is meant to relieve the main processor when it comes to measuring motion data. Lastly, the 5s introduces an improved iSight rear camera and FaceTime HD front-facing shooter, but we'll get to that later in the review.

That leaves one severely underrated improvement: the 5s' global LTE support. In total, Apple will offer the device in four different SKUs, each designed for different regions and mobile operators. The widest-reaching of the bunch -- the A1453 -- supports 13 LTE bands, in addition to penta-band DC-HSPA, quad-band GSM / EDGE and even quad-band CDMA / EVDO rev. A / B. In fact, this version can technically work on all four major US LTE networks. Apple tells us this model will be sold locked on Sprint, but don't expect to see an unlocked A1453 in the US anytime soon -- that honor will go to the A1533 GSM version. The A1533 will come in GSM and CDMA flavors, and will be sold on AT&T, T-Mobile and Verizon. Each one will have 11 LTE bands (yes, it'll include support for all four major US LTE networks as well). Meanwhile, the A1457 is destined for Europe, while the A1530 is tailored for Asia; neither one has support for the most common US LTE bands. As a sidenote, the 5c will also be offered in four models and will support the same bands.

Rounding out the spec list, the iPhone 5s features Bluetooth 4.0, aGPS and GLONASS for navigation, dual-band 802.11a/b/g/n (no ac support this time around) and options for 16, 32 or 64GB of built-in storage. As expected, it doesn't come with NFC, wireless charging or a microSD slot. It also comes in three color options, including silver (just like on the iPhone 5), space gray (gunmetal gray with black highlights on the top and bottom) and, of course, gold. Unsurprisingly, that gold model has received the lion's share of the attention, even since before it was officially revealed. After all that, though, it's much subtler than we ever expected. What we're saying is, while our review unit was silver, we definitely would not have minded taking one in gold.

Touch ID

There's a reason you don't often see fingerprint scanners in smartphones: in the past, they've proven to be unreliable, often causing more aggravation than they're worth. In particular, we're thinking of the Motorola Atrix 4G, which featured a optical capacitive fingerprint scanner that required you to swipe your finger over the sensor, often several times, and with minimal success. But now here's the iPhone 5s, with a most intriguing -- and perhaps most controversial -- feature: its Touch ID biometric sensor. So are users in for the same frustration?

As it turns out, not really. In a clever move, Apple integrated a state-of-the-art capacitive fingerprint sensor into the home button itself and protected it with a sturdy sapphire crystal overlay. It's embedded so well, in fact, that the giveaway that it's a fingerprint reader is the silver ring encircling the sensor. That steel ring acts as a trigger, which detects your finger and then initiates the scan. Once it's activated, the sensor is capable of taking high-resolution pictures of your fingerprint from any angle, which it then sends back to the A7 chip for analysis. The images captured by the scanner show the first layer of skin beneath the dead cells sitting on top -- your sub-epidermal skin layer -- not the layer of dead skin sitting on top - , rendered at a stunning 500 ppi.

The setup process is simple: it typically took us less than a minute for the phone to learn our prints. The phone can memorize up to five different fingers (or thumbs), and they can belong to the same person or multiple people, depending on how many friends and family members you'd like to grant access. The training process may sound cumbersome at first, but it gets easier after just a few tries. First, you start by placing your finger on the home button several times -- it usually took us six or seven repeats -- and then, once the phone has enough information, it asks you to put your finger on the button at different angles. This can be done by rolling your finger from one side to another, or lifting your finger on and off a few times. After that, you'll see the final version added to your list of learned prints -- fortunately, you can rename each one so you don't forget which one is which. In the rare case that the scanner isn't able to read your finger, you'll need to set a passcode to ensure you can still get into your phone.

Sure, fingerprint scanners are cool to geeks like us, but are they really useful, or are they just a gimmick? Perhaps they're a little of both, and besides, nobody's going to force you to use it if you prefer a standard passcode or the ol' slide-to-unlock gesture. However, Touch ID is meant to give your phone an added layer of protection (provided you didn't already have a passcode, of course) while shaving a couple seconds off the unlock process. It also comes in handy for purchasing iTunes content: you can buy apps, music, books and more without having to type the entire password in each time.

And it is indeed fast: the scanner was able to pick up all of our fingers in fractions of a second and from any angle. It's so natural, in fact, that we almost forgot that passwords and unlock screens even existed on the 5s; on countless occasions we tried to unlock the iPhone 5 and 5c with the scanner before realizing that we had to use the "old-fashioned" slide-to-unlock method. It's not perfect, however: the scanner didn't work when our fingers were wet or only partially on the home button, although we didn't experience any problems with clammy fingers in humid conditions. (Update: fun fact -- it also technically works with toes, though we're not sure why you would want to do that.)

There are still some privacy concerns, which Apple has addressed by stating that all of its captured fingerprints are converted into a digital signature, which is then encrypted and stored in just one specific section of the A7 chip. In other words, it doesn't get uploaded to Apple's servers or to iCloud. And -- not that we expect this gruesome a fate -- chopping off someone's fingers won't work, either; sorry, enterprising thieves, the sensor can only pick up living tissue. Additionally, you'll have to enter the passcode if your device has been rebooted, or if you haven't unlocked it in more than 48 hours.

With that said, we were disappointed to see that there isn't a way to require both a fingerprint and a passcode; a conventional string of numbers would offer an optional second security layer for those who don't yet trust Touch ID. We'd also like to see Apple open up the API, since there are plenty of app developers just waiting to take advantage of this feature.

Camera

Apple has always taken an interesting stance on the iPhone's imaging capabilities: make it good, but keep it simple. This is in stark contrast to Android and Windows Phone flagships, all of which boast tons of customization options, along with more unique features. Think UltraPixels, ClearPixel, PureView and so on. This isn't Apple's way, like it or not, but for people who buy iPhones, the company's imaging prowess seems more than sufficient.

Like the iPhone 5 and 4s before it, the iSight rear camera in the 5s offers a maximum resolution of eight megapixels. However, it benefits from a larger pixel size (1.5µm vs. 1.4µm) and larger aperture (f/2.2 vs. f/2.4). Between those two improvements, Apple claims the 5s benefits from a 33 percent increase in light sensitivity. In other words, your daylight shots won't be any more detailed than they were before, but pictures you take in dimmer settings will be a clear improvement over what you're used to on the iPhone 5. In theory, at least. But does the 5s camera live up to Apple's promises?

First, let's tackle the camera's low-light performance. The shots we took with the 5s were consistently better than what we took with the 5: they were sharper, with finer details, more natural colors and far less noise. As you might expect, our daylight shots were roughly on par, though there were a few times when the 5s won out by a slight margin, offering just a little more detail. All told, the 5s plays in the same league as all those other flagships with a bigger emphasis on imaging. Even so, our sample shots still showed more noise and less detail than the same images taken with the Nokia Lumia 1020. The 5s also does a good job of reproducing color, but it's not the best performer in this category, either. Make no mistake, though: the iPhone has been -- and continues to be -- great as a simple grab-and-go camera. It may not be a best-in-class performer, but the vast majority of iPhone users will still be happy. (Update: we've uploaded a ZIP file with full-res images taken on the iPhone 5s.)