Sony is one of very few companies producing small-screen flagships and the Sony Xperia Z3 Compact was its best yet, thanks to a great screen, a good design, impressive battery life and excellent performance.
But now the Sony Xperia Z5 Compact has been unveiled and it's set to improve on the Z3 Compact in myriad ways, from its specs, to its camera and more.
The Sony Xperia Z5 Compact is, as the name suggests, designed to be small and it's certainly that at 127 x 65 x 8.9mm.
It also sports a fairly premium build, with a frosted glass back in white, black, yellow or coral and a familiar unibody design. IP68 certification ensures it can get dusty or fully submerged in water and live to tell the tale and it even has a capless microUSB port, for easier charging.
The Sony Xperia Z3 Compact has a very similar design, with a glass back and a translucent plastic edge. The dimensions are almost the same too, at 127.3 x 64.9 x 8.6mm.
It even shares its newer siblings IP68 certification, though it doesn't have a capless microUSB port and the power button is a silvery sliver here, while on the Xperia Z5 Compact it's a little larger to accommodate a new fingerprint scanner.
Both the Sony Xperia Z5 Compact and the Sony Xperia Z3 Compact have a 4.6-inch 720 x 1280 IPS display, so there shouldn't be much difference between the two.
They're not full-HD, but given their fairly small size there's less need for that and with TRILUMINOS technology they deliver bright, vivid colours.
Power and performance
Both handsets have 2GB of RAM, but while the Sony Xperia Z3 Compact has a now slightly dated quad-core Snapdragon 801 processor, the Sony Xperia Z5 Compact has the recent octa-core Snapdragon 810 chip.
Not only is that faster, but it's 64-bit, while the 801 is just 32-bit, and it's coupled with an Adreno 430 GPU, while the Xperia Z3 Compact has a lesser Adreno 330 GPU. So the Z5 Compact should be a slicker performer, though the Z3 Compact never felt particularly lacking.
The 20.7MP camera on the Sony Xperia Z3 Compact is reasonably competent, with a Superior Auto Mode capable of accurately deciding which shooting mode you should be on and a high ISO rating for solid low-light performance.
There are numerous shooting modes and settings, while video can be filmed in up to 4K and you get a 2.2MP snapper on the front.
The Sony Xperia Z5 Compact takes things up a notch though with a new 23MP sensor. Its 12800 ISO rating is a match for the Xperia Z3 Compact and like that phone it can shoot video in up to 4K.
But it has a few new tricks up its sleeve, such a super speedy autofocus, improvements to low-light photography and a better version of SteadyShot, for smoother video. The front-facing snapper has also had a boost, as the Xperia Z5 Compact has a 5MP wide-angle one.
OS and features
Both the Sony Xperia Z5 Compact and the Sony Xperia Z3 Compact run Android 5.1 overlaid with Sony's own UI, so there's little difference here.
They also include a similar selection of features, such as PS4 Remote Play, High-Res audio and the ability to upscale lower resolution tracks to near High-Res quality.
The main feature the Xperia Z5 Compact has which the Xperia Z3 Compact doesn't is a fingerprint scanner. Not only can this unlock the device, but it can also be used to authorise online payments.
The Sony Xperia Z5 Compact has a 2700mAh battery designed to last for up to 2 days and with the help of STAMINA mode it can potentially keep going for even longer.
It's ever so slightly bigger than the 2600mAh juice pack in the Sony Xperia Z3 Compact and that phone already lasts around 2 days with moderate use, making it one of the longer-lasting smartphones you're likely to find.
The Xperia Z5 Compact has an extra trick though, as it also supports Quick Charge 2.0, allowing you to get up to 5.5 hours of usage from a 10 minute charge.
Price and availability
You can pick up the Sony Xperia Z3 Compact for £429/$469.99/AU$699 SIM free direct from Sony and if you shop around you can potentially find it for quite a lot less.
The Sony Xperia Z5 Compact will be available in October and while Sony hasn't revealed the price yet there's a good chance that it will retail for around what the Z3 Compact costs now, with the older phone likely to drop in price in turn.
With more power, a new camera, a fingerprint scanner, a slightly bigger battery, fast charging and a capless microUSB port the Sony Xperia Z5 Compact looks to be a significant upgrade over the year old Xperia Z3 Compact.
The Z3 Compact is still a fantastic phone and is likely to be all the cheaper once the Z5 Compact hits stores, but if you want a premium Android handset in a smaller size the Sony Xperia Z5 Compact could well be the new king.
Sign up to receive daily breaking news, reviews, opinion, analysis, deals and more from the world of tech.
James is a freelance phones, tablets and wearables writer and sub-editor at TechRadar. He has a love for everything ‘smart’, from watches to lights, and can often be found arguing with AI assistants or drowning in the latest apps. James also contributes to 3G.co.uk, 4G.co.uk and 5G.co.uk and has written for T3, Digital Camera World, Clarity Media and others, with work on the web, in print and on TV.