Sony refocuses its lineup with the lean, mean Xperia X and the beefy Xperia X Performance.

Mobile World Congress

In the past, Sony's Android phones have fallen into one of a few categories: The super-high-end Xperia Z series, and mid-level offerings like the Xperia M and C series. And while its premium phones have generally been decent, the Japanese company had yet to challenge in the emerging mid-to-high-end space — the stomping grounds of the Motorolas and OnePluses of the world.

That changes today, with the unveiling of the Xperia X at Mobile World Congress in Barcelona. The X takes the core of Sony's design language and feature set and transforms it into a pocket-friendly (and presumably more wallet-friendly) product. And the result is something that's worth paying attention to. Read on for our first impressions of the Sony Xperia X and X Performance.

Externally, the Xperia X takes a bunch of design cues from the Xperia Z series, with the latest iteration of its symmetrical "OmniBalance" design language. On the front, there's not much going on besides a beautiful 5-inch, 1080p display and front-facing speakers. The back is furnished in metal, in a break from the firm's usual glass-backed designs. And there's a metal-effect polycarbonate trim framing the whole assembly. It's a simple design, but it works, and it's remarkable how much more ergonomic the X feels than many of the Z-series phones.

That's partly due to the gentle curve of the glass towards its edges — an effect called "2.5D glass" by some manufacturers. Whatever you call it, it's a more natural fit for the human hand than the sharper edges of some other Xperias. The X's 5-inch size and minimal horizontal bezels also makes it easy to one-hand, though the plastic sides can feel a little slick at times.

Xperia X

Lightly curved glass edges and a a smaller form factor make the Xperia X the most hand-friendly Xperia yet.

Around the back there's a 23-megapixel Sony Exmor RS sensor — it's an updated version of the sensor found in the Xperia Z5 series, making it a capable shooter by any standard. But in the X series, Sony has enhanced it with motion-tracking autofocus features — a combination of hardware and software — which can keep track of objects and keep them in focus, even when they're moving erratically. Also a big deal is the move up to a 13-megapixel Sony sensor around the front, allowing for even sharper selfies.

When it comes to core specs, the Xperia X runs an octa-core Snapdragon 650 chip — a new, more powerful mid-range SoC from Qualcomm that makes use of faster ARM Cortex-A72 cores in addition to low-powered Cortex-A53s. That's paired with a new and snappier Adreno 510 GPU. Bottom line: You're getting significantly faster performance (and likely longer battery life) than the Snapdragon 615 variants found in most mid-level Android phones. The Xperia X teams its processor up with a hefty 3GB of RAM and 32 or 64GB of storage, with microSD expandability.

The X Performance adds a Snapdragon 820 and water resistance.

For those who need to be at the cutting edge of smartphones, the Xperia X Performance takes the X's design, display, camera and form factor and augments it with a Snapdragon 820 processor and water resistance capabilities. Sony reps tell us that aside from these internal changes — and a brushed metal pattern on the back of the black and silver X Performance models — the two phones are identical.

Sony also promises a return to "two-day" battery life with the Xperia X, thanks to a 2,620mAh internal battery which should complement the phone's efficient internals. And like the Z5 series, there's a side-mounted fingerprint scanner for biometric security.

When it comes to software, it's no surprise to see the Xperia X running the latest version of Android, 6.0.1 Marshmallow. But Sony's UI has grown in the past year, with brighter colors more Material Design influence and lighter, more modern icons and wallpapers. The core experience is best though of as near-vanilla Android with a sprinkling of Sony apps and features to link into the company's content and services ecosystem. The difference this time around is that many of the apps have been given a much-needed visual revamp.

So overall, the Xperia X (and the X Performance, in what little time we had with it on the show floor) look like compelling additions to Sony's lineup.

The relationship between the Xperia X and Z series is a little complex. If we had to guess, we'd imagine the X might supersede Sony's line of "Compact" phones — and if that happened, it wouldn't be a bad thing. It's the right product at the right time, and we look forward to spending more time with it later this year.

There's no info on pricing for the X or X Performance just yet, but UK carriers including Three and Vodafone have already begun to announce that they'll range the device, and it's expected to hit the U.S. this summer.