Asus Zenbook UX21 review

The Zenbook is Asus' first foray into the Ultrabook world, offering powerful guts wrapped up in a super-slim and sturdy aluminium shell.

Asus is undoubtedly hoping to challenge Apple's dominance of the ultra-light market by offering the UX21 for £849, undercutting the similarly specced 11-inch MacBook Air by £150. We think it just might have a shot.

The Zenbook UX21 packs a 1.6GHz Intel Core i5 processor with 6GB of RAM. It will be available from 21 October.

Design and build quality

Like all Ultrabooks, the Zenbook is designed to be slim, light and powerful enough to tackle demanding tasks. The UX21 is very slender, measuring only 17mm at the thickest point at the back and tapering down to 3mm at the front, which is as slim as the 11-inch Macbook Air.

That is a seriously slim piece of kit.

The UX21 is packing an 11.56-inch screen, so the chassis has been kept as small as possible. With a width of only 297mm and a depth of 196mm, it's small enough to slide into the most diminutive of bags without a second thought. The 11-inch MacBook Air has pretty much identical dimensions, so you can happily play 'ultra-light Top Trumps' without fear of an easy defeat.

The UX21 is machined from a single piece of aluminium, rather than being bolted together from various pieces of plastic and metal like regular laptops. We poked, prodded and bent the UX21 and didn't detect any flex in the body or in the lid, making it feel like a really well-built chap.

It certainly seems sturdy enough to cope with a rough-and-tumble weekend. But just to make sure, we took it away on a rough-and-tumble weekend. This involved the UX21 being chucked in and out of bags and cars, and being aggressively manhandled by 19 twenty-somethings in a big house in the middle of the Welsh countryside. The result? Not a mark on it. Splendid.

It's an understated look, but we're really keen on it.

The Zenbook weighs a not insubstantial 1.1kg. It feels surprisingly heavy when sat in your hand -- we naturally expected something so small to weigh much less -- but that weight comes from the solid metal construction.  We'd much rather have a machine that's a few grams heavier but built like a lumberjack than a featherweight affair that snaps at the first sign of trouble.

Rather than opt for the standard brushed metal finish, the lid has a rather unusual spun metal finish -- the Asus logo sits in the middle of an ever-decreasing circle. At first, it seems like a weird look, but we quickly got used to it and had to admit that, all in all, this laptop is stunning.

The 11.6-inch screen has a 1,366x768-pixel resolution that's both pleasantly sharp and extremely bright. Colours were handled well, so it'll do the job for Web browsing and streaming TV shows from BBC iPlayer. It doesn't have the deepest black levels we've ever seen, though, so if you want a full movie experience, you might want to hook it up to a big TV via the micro HDMI port.

The spun metal finish is unusual and classy.

If 11.6-inches doesn't quite cut it for you, then you can go for the Zenbook UX31, which offers a 13.3-inch screen with a higher resolution as well as packing an Intel Core i7 chip for tackling more demanding tasks. This will set you back an extra £150 though.

Keyboard and trackpad

The keyboard uses square, isolated keys that at first glance look like they're made out of the same metal as the chassis. Sadly though, they're not, and are actually the more standard plastic. They're set quite low and close together, meaning that it doesn't always feel clear when you've pressed a key. This can cause a few mistakes when touch-typing at speed.

We got used to the feel of the keys pretty quickly, though, and gradually made less and less mistakes, but we much preferred the feel of the MacBook Air's keyboard. Unlike the Air, the UX21's keyboard isn't backlit, so typing away in a dark room isn't going to be easy. Best to get up and pop a light on.

The keyboard isn't the best we've ever used, but it's a minor complaint.

The trackpad is a particularly massive, clickable glass affair. It takes up all available space, so it'll be handy for those of you who love sending your cursor frantically flying across the screen. It's pretty responsive and supports various multi-touch gestures that are handy for quick use.

Clicking with two fingers acts as a right-click, swiping to the right with three fingers displays all open programmes and windows in a cascading wheel, and swiping down with three fingers takes you instantly to the desktop.

Around the edge of the UX21 you'll find a USB 2.0 port, a USB 3.0 port, a micro HDMI and mini VGA ports, and a mic in/headphones out jack. There's no Ethernet port to be found but it comes with a handy USB Ethernet adaptor in case you need to hook it up to your router for speedy downloads.

That's right, there is a huge trackpad.

The USB 3.0 port uses what Asus calls USB Charger+ technology that apparently charges devices like your mobile phone much faster than usual.

We plugged in our iPhone 4 for a bit of a juice-up and found that it did charge a little quicker than it otherwise would -- if you often find yourself needing a quick top-up to save your phone from cutting out, it will be a welcome addition.

Performance

The 11.6-inch UX21 we had our excited, sweaty palms on was running an Intel Core i5 processor teamed up with 4GB RAM. Those are some seriously strong specs for a machine of this size, so we battened down the hatches and dived in to see what this guy can do.

We booted up the PCMark05 benchmark test to shed some light on the processor's firepower and were given the extremely pleasing score of 9,802. That's some serious grunt, and beats the scores of bigger laptops such as the Acer Aspire 5755G, whose 2GHz Core i7 processor managed 9,049 on the same test.

It also easily beat the score given by Asus' own NX90Jq -- a monstrous machine packing a quad-core Intel Core i7 processor and 6GB RAM. The NX90Jq may cost an eye-watering £2,000, but it only managed to score 7,218.

A handy graph showing the results of various models in the PCMark05 benchmark test.

Sadly, we can't run the PCMark05 benchmark on the Air as it is Windows-specific, but the Geekbench test can run across both platforms. On this test, the UX21 gave an impressive score of 5,828, although that doesn't quite beat the 6,285 we achieved with the 11-inch Air we tested. The model we had packed a 1.8GHz Intel Core i7 processor, however, so we would expect a considerably better performance.

Although the Air did just beat the Asus, it didn't beat it by as much as we'd expect considering the more powerful components in the Air, which really emphasises the amount of power Asus has managed to squeeze out of the silicon. We dug around and happened upon a 13-inch Air with a 1.7GHz Core i5 processor and 4GB of RAM. This managed to achieve 5,919 on the Geekbench test -- only a very slight improvement over the Asus, considering the faster clock speed.

Annoyingly, Asus isn't allowing you to customise the specs of the Zenbooks online -- the 11.6-inch packs an i5 chip, the 13.3-inch packs an i7. We were really keen on the power of the Core i7 11-inch MacBook Air and would love to see the same processor being offered in the more bag-friendly 11-inch Zenbook. If you do want the extra grunt, you'll have to opt for the 13.3-inch UX31 Zenbook.

The UX21 has several ports, you'll be pleased to know.

It would also be good to have seen Asus offering a Core i3 model, which based on the current prices of Zenbooks, would probably have been served up for around £650, making it a very affordable opening into the Ultrabook world. Asus says it wants to avoid confusing customers by keeping the product line-up simple; each size has only one specification. It's surely not that confusing to offer two power options for each size.

Graphics

There's no dedicated graphics card inside the UX21, but the built-in Intel HD graphics will offer a helping hand with video and 3D games. We booted up the adrenaline-pumping rally game Dirt 3 and sent our car careering through the Finnish hills. The frame rates stayed roughly at around 13 frames per second, which really isn't good enough for this sort of intense game, resulting in the action seeming juddery and slow.

If you want to spend your train journey playing the latest first-person shooters with the graphics settings ramped up to the max, the UX21 won't be for you. We fired up Half Life 2: Episode Two, though, and found that frame rates stayed around 50 frames per second, only dipping to 35fps in the more intense sequences, making the game perfectly playable. Half Life 2 is getting on a bit now in the gaming world, so if you're a fan of the slightly older titles, the UX21 should do the trick well.

Another handy graph! This one shows the Geekbench benchmark results. The UX21 didn't do as well in this one, but it's against very stiff competition.

In general, we found the performance very speedy and were able to run high-definition video, Spotify, and Web browsing with numerous open tabs -- including video streaming -- all at once and didn't notice any slowing down. Its lesser performance in the gaming arena means that it is particularly suited to those after general processing power, rather than a dedicated gaming machine.

Storage and battery life

Asus has shoved in a 128GB solid state drive (SSD), which is smaller and faster than traditional hard disk drives (HDD). This speed helps the Zenbook achieve a resume from sleep time of around two seconds, which is particularly handy if you just need to bang out a quick email and don't want to wait for ages for the thing to start up. In our tests, it also managed to start up in 21 seconds from being switched off to seeing the desktop, which is a pretty good time.

There are no moving parts in SSDs, so they are much more economical with power than HDDs, meaning that the Zenbook can last about a fortnight on standby. The MacBook Air boasts a 30-day battery life on sleep mode, which beats the Zenbook by a healthy margin, although we can't really think why you'd want to leave your laptop sat in standby for a month.

It also has a handy feature of automatically saving your work when the battery drops below five per cent. That's definitely going to appeal to those of you who -- like us -- have accidentally lost work when playing the dangerous game of travelling without a battery charger.

As a machine designed for its supreme portability, it's fair to expect that the UX21 can last a while away from a plug. We ran our battery test and the UX21 managed to keep going for 2 hours 24 minutes before giving up the ghost. It's a hugely demanding test, though, and we achieved more than double that result with cautious usage on the road.

Conclusion

The Asus Zenbook UX21 is undeniably a beautiful piece of kit. It's slim, lightweight and sturdy enough to be chucked in a bag and carted off around town. It also offers a serious punch of power from its Intel Core i5 processor and boasts a very competitive price, making this chap an excellent rival to Apple's MacBook Air.