If you thought the Samsung Galaxy Note 3, HTC One Max and Nokia Lumia 1520 were big phones (and you'd be right), Sony has just out done the lot with the Xperia Z Ultra. The phablet has a whopping 6.4in display so is closer to the size of a Nexus 7 than a Nexus 5.

The Xperia Z Ultra looks much like the regular Xperia Z1 but super-sized. It still has the power and volume buttons on the right-hand-side and stylish brushed aluminium edging and a glass rear cover. See: What's the best phone you can buy in 2013?

Sony has ensured the device is also dust- and waterproof like its brothers so, to this end, the ports are all covered up with flaps. The only one which isn't is the headphone jack which cleverly doesn't require one. It's oddly positioned on the side of the smartphone though which proves awkward. There's also a pair of metal contacts for use with a charging station.

The Xperia Z Ultra is astonishingly thin at 6.5mm (the Xperia Z1 is 8.5mm) which helps to keep the weight down but it still tips the scales at 212g. Build quality, like the other Xperia phones and Sony products in general, is excellent. Premium materials put together with care results in a premium device.

See also: Sony Xperia Z review.

Sony Xperia Z Ultra: Hardware and performance

So you get plenty of real-estate with the Ultra and the Full HD display looks great, just like the original despite the drop in pixel density. This is all great if you want to watch a film or browse the web. However, the handset can't be used effectively with one hand and you look like a bit of a chump holding it up to your face to have a phone call – two major issues.

Unless you're Hodor from Game of Thrones (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. The phablet is also very precarious when held in one hand.

An advantage to this screen is its rather neat ability to be used with a regular pencil. It works very well avoiding dirtying the screen with fingerprint marks. 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. It's not a flawless experience with a bit of lag when drawing or using the handwriting recognition but nevertheless, it's a great feature.

Insanely large screen aside, the Xperia Z Ultra has some decent internal specifications. Keeping up with other top-end handsets, it's got a 2.2GHz Qualcomm Snapdragon 800 quad-core processor, Adreno 330 GPU and 2GB of RAM.

Internal storage is a fairly regular 16GB and there's a microSD card slot which can take up to 64GB cards. Also under the bonnet is an NFC chip, 11ac dual-band Wi-Fi, Bluetooth 4.0 and support for 4G LTE networks.

An optional NFC-enabled SBH52 Bluetooth Handset lets you leave the Ultra in a bag or pocket but still make calls, view text messages and listen to music stored on the main unit; It's even a stand-alone FM radio. A much more wieldy way of using the device but adds £59 to the total cost.

Sony Xperia Z Ultra: Cameras

The main camera has been downgraded to 8Mp compared to the Xperia Z1's 20Mp shooter and even the older Xperia Z's 13Mp. Considering the high price of this handset, we expected it to at least stay the same. Unfortunately photos and videos from the Z Ultra are lower quality than other 8Mp smartphones such as the iPhone 5C.

Sony's Superior Auto mode will do all the work for you but is strangely limited to 7Mp images. You'll have to switch to 'Normal' to gain access to all 8Mp and select 'Video camera' to be able to change what resolution you shoot video at. There are a number of other modes for features like burst, panorama and scene select.

It's a shame that with a phone this big, Sony hasn't included a dedicated camera shutter button and for some strange reason there's no LED flash.

We can't help but feel the photography performance of the Z Ultra is a bit lacking, compared to older Xperia devices and competitors. Here's a sample photo and video both captured with the Superior Auto mode.

Click to enlarge

Sony Xperia Z Ultra: Software

The Xperia Z Ultra is running Android 4.2 Jelly Bean with Sony's usual skin on top including the Walkman app, battery saving Stamina mode and Sony's Entertainment Network. Sony's wallpers and widgets are particularly good and the notification bar gives access to settings such as Wi-Fi, Bluetooth and screen brightness.

It's a stylish interface which is intuitive to use, striking a nice balance between providing additional features and overwhelming the user. Our main complaint is the pre-loaded apps like McAfee and OfficeSuite which you might not want. However, you can simply uninstall these so it's not totally forced.

Android 4.2 is a little out of date now but Sony has confirmed that version 4.3 will be rolled out to devices including the Xperia Z Ultra in December and Android 4.4 KitKat will arrive sometime after this but no timeframe has been given.

See also: Sony Xperia smartphones to get Android Jelly Bean and KitKat upgrades.

Sony Xperia Z Ultra: Battery life

A phone this big means plenty of space for a large battery pack and therefore battery life. The Nokia Lumia 1520 is fitted with a huge 12.9Wh battery but despite being larger, the Xperia Z Ultra has an 11.3Wh capacity. That's not much bigger than the much smaller LG G2.

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.

Luckily Sony includes power management software, the main feature of which is a Stamina mode which minimises battery use by disabling functions like Wi-Fi and mobile data when the screen is off.

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