Sony has a phone problem. It keeps announcing replacements for phones that no one bought, or couldn't buy, or refused to buy because they lack a fingerprint sensor.

At Mobile World Congress in Barcelona this week, Sony has added four new phones to its ecosystem, all with names that are sure to confound its eventual owners and detractors alike. One only, the Xperia XZ Premium, is truly interesting — it has a 4K display that supports HDR — while the other three, the Xperia XZs, Xperia XA 1, and Xperia XA 1 Ultra, have a few notable features inside iterative spec sheets and limited availability, especially in the U.S.

We'll start with the most interesting. The Xperia XZ Premium takes the shell of the XZ announced last September and increases the size. Its 5.5-inch display has a 4K resolution, and it's one of the nicer displays we've ever seen on a phone. In fact, this one is compatible with the latest HDR specifications, meaning that it will output supported content in more vivid colors with better dynamic range. Built with a double-anodized metal frame, both the front and back are outfitted with Gorilla Glass 5, and each of the two colors — Deep Sea Black and Luminous Chrome — shimmer off the glass back in a parade of reflectiveness. This is possibly the most mirror-like phone ever created.

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To reinforce its high-end target demographic, the phone comes with a brand new Snapdragon 835 processor, 4GB of RAM and 64GB internal storage standard. It's IP68 water and dust resistant, and in all markets but the U.S. has a side fingerprint sensor. Basically, if you've used the Xperia Z5 Premium, this looks remarkably similar, but for the rounded top and bottom, and a nicer-looking camera array.

That camera, which Sony says is all new in the Xperia XZ Premium, is once again the art of iteration. This book could have been written two years ago. A Sony IMX300 sensor — the same one found inside that aforementioned Xperia X5 Premium — has been slightly altered for this device, lowering the megapixel count from 23 to 19, affecting the size of the pixels to offer better low-light performance.

This is possibly the most mirror-like phone ever created.

And while there's no OIS in here, Sony claims that its new 5-axis stabilization system, known as SteadyShot, should do the trick.

The other trick is "Motion Eye", a way of increasing bandwidth between the camera and the phone's memory bus by five times, allowing for a surfeit of incoming data. That allows for predictive capture — the idea of caching frames while the viewfinder is open and only capturing the four frames around the shutter button — in addition to the absolutely insane 960fps slow-motion feature, though only at 720p.

These are great features, but nothing particularly noteworthy — and we're always suspect of Sony's camera claims until we have the phone in hand; we're been burned too many times before — and Sony, because of the dearth of Snapdragon 835s in the market right now, isn't shipping the Premium until late spring, likely late May or early June.

There's no price right now, either, but based on the $699.99 price tag of the other flagship being launched this week, the Xperia XZs, we're not holding out for anything below $850.

That Xperia XZs is still a great-looking phone, but it's less interesting than then Premium model. That's because it's a minor refresh of the Xperia XZ announced just six months ago.

In his review of the Xperia XZ, Alex Dobie called it plainly:

The problem for Sony, like so many other Android manufacturers, is the fact that Samsung's absolutely crushing it this year. Sony's camera is great, but it's not the best. Same deal with its screen, its build quality and its battery life. And U.S. buyers once again get the short end of the stick, as Sony cheaps out on fingerprint security.

Oh, that's right, neither the Xperia XZ Premium nor the XZs have fingerprint sensors in then U.S. Phones sold in the rest of the world get the feature, but it's still an inexplicably omission, one that Sony refuses to justify.

The Xperia XZs looks exactly the same as its predecessor — same design, 1080p display — but comes with a slightly more robust 4GB of RAM and 64GB internal storage to augment the Snapdragon 820 processor. The new 19MP "Motion Eye" camera is here, too. Both it and the Xperia XZ Premium will run Android 7.1.1 at launch, with Sony's increasingly tolerable

The Xperia XZs will be available in the U.S. unlocked at Best Buy and Amazon for $699.99 starting on April 5.

Sony's two other devices announced at Mobile World Congress are less interesting but could prove considerably more popular. The Xperia XA 1 is a follow-up to the popular 5-inch device released last year, and the borderless 720p display is now powered by a MediaTek Helio P20 processor, an improvement over the P10 of the original. There's also 3GB of RAM and 32GB of internal storage, nice bumps from last year, too.

A new 23MP rear shooter has trickled down from more expensive Xperia X series devices as well, making the $299.99 Xperia XA 1 a nice upgrade when it goes on sale May 1 at Best Buy, Amazon, and B&H Photo.

Finally, a larger version of the XA 1, affixed with Ultra, will debut in late spring. The 6-inch 1080p display is the showpiece here, and there's no question that the device is more compact for it, but this is still a big phone. The phone has the same specs as the XA 1 but for the optically stabilized 16MP front-facing camera, which also comes with an LED flash.

While it would be easy to dismiss these phones as simple evolutions on existing designs, Sony clearly understands where its strengths are these days and is heavily playing into them. The Xperia XZ Premium brings back the high-end flash of the Xperia Z5 Premium while pushing display technology forward to support HDR, while embracing the latest generation SoC from Qualcomm. The other three phones are nice upgrades, but will most likely get lost in the shuffle of a very competitive handset market.

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