Once upon a time the great race in mobile was to build the phone with the most megapixels to its name. Now the race seems to be for the highest resolution display. Enter Sony and the Z5 Premium, its new phablet-style smartphone with the 4K UHD display the rumours suggested we could expect and, of course, the ability to shoot 4K video, too. With a resolution of 3,840×2,160 pixels and a 5.5-inch display, that means a 808 pixels per inch (ppi). Wowser!

The new flagship, meanwhile is the Z5 and the trio is rounded out with the Z3 Compact. All three devices are waterproof — something we love about Sony’s devices, especially since they found a way to maintain the waterproofness without the fiddly port covers required by earlier Xperia devices — and all three most a new 23-megapixel camera sensor that promises better low-light performance and autofocus times as fast as 0.03 seconds.

Sony’s also punting something called “clear image zoom”, which looks like a cross between digital zoom and post-processing upscaling that lets users zoom in on images without losing detail or seeing the image pixelate like they tend to on current mobile phones. We’ve all but discounted digital zoom to date, and with good reason, it’s absolutely rubbish and the sort of thing we make family members turn off on their compact cameras immediately, so we’re curious to see how Sony’s offering performs.

Video’s also gotten an update with further developments to Sony’s SteadyShot technology and something called “Intelligent Active Mode”. And both video and stills are meant to offer better low-light performance, something we’ll put to the test when we get our grubby paws on a review device.

The Z5 includes a 1920×1080 5.2-inch display while the Z5 Compact comes with a 720p 4.6-inch display. The Compact comes in the most exciting colour options, namely yellow, coral, white and black. The Z5 and Z5 Premium will be available in green, gold, white and black.

As expected, Sony’s also introduce a fingerprint sensor on the power button of each device, something the likes of Samsung and Apple have offered for a while now. Stuff got the chance to handle the new devices last week and we were suitable impressed with the build quality. Sony’s gone for the glass-front-and-rear and metal-around-the-edges look its favoured in recent years, but has added an etched Xperia logo.

The Z5 Premium is a little thicker than we’d expected, but that’s no doubt because of the 3,430mAh battery it’s packing. That’s another thing we’ve long liked about Sony’s devices: the impressive battery life. All of the new devices also include support for rapid charging, something that’s impressed us on Samsung’s latest handsets. Less impressive is Sony’s decision to opted for 32GB of internal memory on the Z5 Premium, but it does support microSD cards up to 200GB.

Audio has also gotten attention across the range, with all three of the Z5 devices offering “high-res audio” and shipping with earphones that include digital noise cancellation. This, again, is something we’ll put through its paces and report the results to you, dear reader.

And like its predecessors, the Z5 range supports PS4 Remote Play, which allows you to continue playing PS4 games on your mobile device assuming you’re on the same Wi-Fi network as your console.We’ve got to admit we’re not convinced the smartphone market really needs a 4K-display on a mobile phone. When we got to play with the Z5 Premium last week we were impressed with the display, make no mistake. Pixels were impossible to discern and the brightness and colour rendition was excellent… but it wasn’t any more impressive than the displays on Samsung’s recent releases.