The phablet has a whopping 6.4in display so is closer to the size of a Nexus 7 than a Nexus 5.The device is essentially a super-sized version of the Xperia Z1, with a few little differences. See also 17 best smartphones: The best phone you can buy in 2013
It's got the same stylish brushed aluminium edging, glass rear cover and a fully dust- and waterproof design. Build quality, like the other Xperia phones and Sony products in general, is excellent. The device is astonishingly thin.
Plenty of real-estate is great for watching films, browsing the web or playing games. However, unless you're someone with huge hands, you're going to have issues trying to use this phone with one hand. It's almost impossible to reach anything in the top half of the display or on the opposite side to your hand.
An advantage of the screen is its rather neat ability to be used with a regular pencil. You can use a pencil just like a stylus and when you are, two options appear in the notification menu to take notes or create a sketch.
Insanely large screen aside, the Xperia Z Ultra has some decent internal specifications. In a nutshell, it offers top-end performance.
Internal storage is a fairly average and there's a card slot for adding more. Also under the bonnet is an NFC chip, 11ac dual-band Wi-Fi, Bluetooth 4.0 and support for 4G LTE networks.
Sony has downgraded the camera compared to the Z1, down to 8Mp. There's no dedicated shutter button despite the size of the device or LED flash. The Xperia Z Ultra is lagging behind rivals in terms of photo and video quality.
The Xperia Z Ultra is running Android 4.2 Jelly Bean with Sony's usual stylish skin on top including some nice wallpapers, handy widgets and well-designed apps. There are a number of pre-loaded apps but these can be easily uninstalled.
Being the size it is, Sony has fitted this phablet with a large 11.3Wh battery. Using the Xperia Z Ultra for general tasks means you'll comfortably get through a day, if not a second.
However, hit the net, catch an episode of a TV show, spend some time gaming or connect with your friends on social networks and the battery level quickly disappears.
Stamina mode minimises battery use by disabling functions like Wi-Fi and mobile data when the screen is off and the metal contacts help you keep the device topped up if you buy a docking station.
The Sony Xperia Z Ultra is a nicely made device but doesn't represent good value for money. The phablet is extremely unwieldy and doesn't have a great camera. Sony would have been better off making this a 7in tablet rather than a 6.4in phone. We award three and a half stars.