It's been over a year since Sony last released a full-sized slate in the form of the Xperia Z2 Tablet. A lot has changed since then. Apple's iPad Air 2 set a new standard for supreme portability, while a flurry of top-quality convertibles made competition in the laptop replacement market ever more fierce.
Like its 2014 predecessor, the Xperia Z4 Tablet is a high-power, low-profile Android device with an eye on the mass market, although the addition of a bundled keyboard attachment suggests that Sony has designs on its being a useful working tool as well.
The most striking aspect of the Xperia Z4 Tablet is just how thin and light it is. At 167x254x6.1mm, it's exactly as skinny as the iPad Air 2, and weighs a mere 393g, over 40g less than its Apple rival, despite being a little longer.
This remarkable feat doesn't seem to have adversely affected the build quality, as it easily weathered satchel rides and accidental drops over the course of an unusually butterfingered week.
The only hint of delicateness we found was some slight diagonal flexing, which occurred only when we forcibly pressured it at opposite corners.
This can largely be attributed to the use of plastic, rather than metal, for the case. That said, the corners have been reinforced with little stainless steel protectors, and we really like the subtle matte texture of the plastic back panel.
The Xperia Z4 Tablet is fronted with a single piece of fingerprint-resistant glass. It's not 100 percent effective, but works well enough to prevent the build-up of irritating smudges.
The single failure of the tablet's design is the lack of connectivity options. You get one microUSB port, one microSD slot and, on the pricier 4G/LTE model, one nano SIM slot. That's it.
Sony isn't exactly gunning to compete with £1,000+ convertibles here, but the Xperia Z4 Tablet's port shortage is a serious limitation on its capabilities as an office productivity aid.
The keyboard helps to make up for this and comes with the tablet as standard. The keys are on the small side, as anyone would expect, but they're not too tiny.
Typing on them quickly becomes second nature, especially to anyone who's ever owned a netbook, and using this laptop setup makes for quicker, easier working than sticking to the screen-hogging touch keyboard.
Cleverly, enabling the physical keyboard changes the Android UI to be more Windows-like, with a taskbar of apps appearing on the bottom left of the screen. There's even a pop-up Recent Apps menu that tellingly resembles the classic Start Menu.
Android will always be a mobile OS, but we appreciate these touches that make the keyboard experience a little closer to that of a PC.
However, the keyboard itself is far from perfect. It connects to the tablet via Bluetooth rather than a conventional dock, and the process of switching on and manually reactivating the keyboard every time we wanted to use it quickly became tiresome.
The keyboard's hinge, which holds the tablet in place with rubbery grips, also feels quite flimsy and wobbly, and we were disappointed to find that the microUSB port on the keyboard's side is used only for charging and doesn't provide the tablet with some additional, much-needed connectivity.
The biggest problem of all is that typing causes the cursor to disappear, and there's a noticeable delay between touching the trackpad and the cursor actually returning. This is just as inconvenient as it sounds when trying to work at speed.
At least there are some benefits to having a Bluetooth keyboard. For one, the two components don't need to be physically touching in order to work together, which will be useful for those who want to type on a flat desk while moving the tablet display up to eye level.
The lack of a physical connection port also enables the tablet to be secured in the hinge back to front, effectively turning the keyboard into a stand for angled touchscreen use.
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