Battery life is more important than ever on Ultrabooks, as the integrated batteries are not designed to be user replaceable meaning you can’t take a spare or easily swap it out when it starts to deteriorate. Thankfully the 13in Zenbook holds its own here, with it managing just a few minutes short of six hours in our non-intensive battery test (various productivity scenarios with screen brightness at 40 percent and wireless radios disabled).
That’s better than both the Acer Aspire S3 and MacBook Air 13in, albeit it's put in the shade by the seven hours Samsung’s Series 9 900X3A brings to the table. Still, it should be enough to get you through a working day with careful use.
Unfortunately, at the time of writing it’s almost impossible to find stock of the UX31 anywhere in the UK, though its little brother, the 11in UX21, is readily available for around £850. Still, that machine lacks the high screen resolution and SDXC card reader of its larger sibling, as well as packing a Core i5 rather than Core i7. In other words, size considerations aside the 13in Zenbook is the one to go for.
Going by its MSRP of £999, the UX31 is excellent value as Ultrabooks/ultraportables go. The 13in Air with the same adapters but a slower Core i5 CPU, for example, will set you back £1,145. Asus faces stiffer competition from the Windows PC camp though, especially in the form of the S3, since Acer will sell you its Aspire Ultrabook with a 240GB SSD for £1,075. However, again the CPU gets a downgrade, you’re stuck without fast connectivity like USB 3.0, the screen resolution is lower (though viewing angles are better) and the Zenbook just wins out on usability too – without even counting the extras you get. Overall then, we’d say the UX31 wins the toss.
If you do want a superior screen and backlit keyboard, the £1,100 Samsung 900X3A is also worth keeping in mind, while if you’re on a budget the £700 model of the S3 is nigh-on unbeatable, being the cheapest 13in Ultrabook by quite some margin.
Asus’ 13in Zenbook comes very close to being the ultimate Ultrabook. It sports a nice design, solid aluminium build, superb connectivity, high-resolution screen, great keyboard and touchpad, class-leading audio and premium accessories such as the stylish sleeve – and all for under £1,000. Given this, its lack of keyboard backlighting can easily be overlooked. Unfortunately, its screen’s poor viewing angles are trickier to forgive, keeping the UX31 from a Recommended Award by a kitten’s whisker.