Sony takes a confident step forward with a new camera, redesigned chassis and fingerprint security

After a shaky start to the year with the Xperia Z3+, Sony needed a great flagship to set its high-end smartphone series back on track. And the Xperia Z5 brings some much-needed advancements, most notably a brand new rear camera and fingerprint security technology.

Sony's iterative march forward continues with yet another solid high-end Android phone — its second in a relatively short space of time. The new Xperia Z5 — the middle child now, sitting between the Compact and the Premium — sports a 5.2-inch 1080p display along with the same leading mobile hardware used across the Z5 line. That means there's a Snapdragon 810 processor paired with 3GB of RAM and 32GB of internal storage, with microSD expandability. As we've come to expect form Sony, the Z5 also packs IP65 and 68-rated water and dust-resistance, with capless ports for microUSB and headphones.

But first, the basics: Like the past three Sony flagships, we're dealing with a 5.2-inch phone with a 1080p resolution display, and unsurprisingly the Z5's screen looks phenomenal. The company could've easily pushed for a denser 2K display, but there's really no need. Besides, there's more to display quality than pure resolution.

At its core, the Z5's design is very similar to the previous generation of Sony high-enders: An aluminum frame encircles the display, with a rounded rectangular design and glass back. The back panel features an all-new texture this time around, though — the "frosted glass" material is slightly grippier and less fingerprint-prone than earlier Xperias, and as a result the phone doesn't get gunked up quite so easily. The plastic segmented corners, necessary for RF visibility, also blend into the metal a bit more seamlessly now, giving the impression of a unified whole.

Xperia Z5

You'll find all the hardware ports in familiar places — buttons on the right, slots for microSD and SIM on the left, and microUSB down below — and this time the power button has been expanded to include a fingerprint scanner. It'll take time to judge the longterm effectiveness of a fingerprint scanner on the side, but the button is ideally situated to make that extra security feel extremely natural. We're also noticing a bit more Xperia branding on that aluminum frame, with Sony's smartphone brand emblazoned on the bottom-left corner of the device.

The biggest upgrade for Sony is an all-new 23-megapixel camera.

The other main hardware change has taken place around the back: Sony's upgraded its flagship's main camera sensor for the first time in three years, moving to a new 23-megapixel Exmor RS sensor with fast auto-focus — as quick as 0.03 seconds, Sony claims — and an f/2.0 lens. This bright lens, combined with the re-tooled sensor, helps the Z5 perform better in low-light conditions, an area in which previous Z-series phones have lost out to the optically-stabilized competition. Our first impressions were generally positive — the Z5 managed to capture plenty of detail in the variable lighting at the Sony booth at IFA, and both focus and capture times were impressively quick. Can it match up to the latest hardware-stabilized phone cameras from LG and Samsung? That's still unclear. And we'll need more time to test the camera thoroughly of course, but it's a good start.

There are also promising signs that the Z5 might not suffer from the overheating issues that affected the Xperia Z3+ at launch. Unlike the Z3+, we haven't spotted any thermal issues within the camera or any other apps on the new handset. In fact, the Z5 units on show at IFA performed admirably, without any of the problematic temperature warnings produced by the older phone. The impact on battery life remains to be seen, however — Sony claims the embedded 2,900mAh cell will get you up to two days, but we've seen the Z3+ fall short of that mark with very similar internals.

On the software side, the Sony UI is pretty much unchanged from what you'll find on an updated Xperia Z2 or Z3 device — Android 5.1.1 Lollipop, and a UI close to vanilla Android, but with a selection of apps to tie into the company's content ecosystem. PlayStation 4 Remote Play, a killer app for owners of Sony's console, returns in all three Z5 handsets, and other apps tie into Sony's photos (PlayMemories) and video streaming (PlayStation Video) services. It's still a phone for the Sony ecosystem, first and foremost.

Xperia Z5

Ultimately, the Z5 represents yet another deceptively important baby step forward for Sony. The physical changes bring "Omnibalance" into 2015 with some interesting design traits, like the textured glass rear and engraved Xperia branding along the trim. Meanwhile the camera upgrades take Sony phones comfortably beyond the photographic capabilities of the past few years. And biometric security means Sony is well-positioned to take advantage of authentication features in Android 6.0 Marshmallow.

We'll have more to say on the Xperia Z5 when the phone launches this October, so stay tuned!