The mechanism for flipping between the ultrabook and tablet modes is the same as before (the screen rotates within the bezel to flip backward and forward). All that's changed is the material, with carbon fibre making up the majority of the chassis and lid and aluminium used for the bezel. The carbon fibre's matte varnish gives it a nice peachskin feel, although you might want to refrain from touching it as it smudges easily.
The XPS 12 is very well assembled; the hinge connecting the screen and chassis is sturdy and the display feels stable within the frame when you rotate it. However, we find the rotation mechanism a bit too sensitive: all you have to do is push on the screen lightly and it starts to rotate. When the display is closed, the device is 24 mm thick, which isn't particularly thin as ultrabooks go. But it's still compact enough to fit in any reasonably sized bag or briefcase. 1.53 kg is a comfortable weight, although we expected it to be even lighter given the materials used.
The backlit chiclet keyboard is well integrated into the magnesium wrist support panel. It offers a nice stroke and is comfortable to type on. The large (100 x 65 mm) touchpad is plenty spacious for navigating on and it recognises all the Windows 8 touch gestures. The touchscreen is responsive and precise, making for a good tablet touch experience.
As always with laptop/tablet hybrids, there are very few ports: just two USB 3.0 ports, a mini-DisplayPort and an audio in/out. For wireless connectivity it has Bluetooth 4.0 and Wi-Fi N with a -45 dBm signal from 5 to 10 metres away and -50 dBm from 20 metres away.
Here's an understatement: the XPS 12 overheats. While running our usual stress tests the body got as hot as 54.6°C on the underside of the chassis, towards the back (39.2°C in the same spot on the topside). Here's another understatement: that will be hot on your lap. Fortunately, while the fan doesn't seem to help keep the climes down, it at least stays quiet at 42 dB max. That's not loud, but you will notice it in an otherwise silent room.
The screen has Full HD resolution (1920 x 1080 pixels) and fairly good contrast (851:1) and brightness (376 cd/m²), enough to counter the glare and reflections caused by the glossy touchscreen.
Grey colour temperature
The colours are a tad warm (6,377 K) and unfaithful (Delta E = 5.4). A Delta E of three or below would mean perfectly faithful, natural colours, so here they're somewhat exaggerated, though not ridiculously so. All in all, this is a fine display that will please all but the most picky buyers (professional photographers and such).
The sound quality through the 3.5mm audio in/out has a remarkable stereo image and great dynamics. All we can criticise about it is a slight touch of distortion when you put the volume up all the way. That said, you aren't necessarily going to do that very often, because the volume is quite high in the first place, much more than most laptops.
The speakers are a completely different story, though. They're tiny and have very little bass for an unbalanced, imprecise sound. The maximum volume is extremely low, yet somehow they saturate like crazy. Even for an ultrabook, this is bad.
Note: The model we were sent to review features an Intel Core i7-4500U processor, 8 GB of RAM, an Intel HD Graphics 4400 chipset and a 256 GB SSD. The comments above refer to all versions of the Dell XPS 12 (Haswell Generation), whereas the sections below apply only to the model we tested. Available configurations may vary depending on the country/region in which you live (see inset below).
The Intel Core i7-4500U is the same processor Dell used in the Inspiron 14 7000 Series. But here it's faster, especially with video compression. In the tests we ran the XPS took 113 seconds less time to compress the same videos as the Inspiron.
That said, we couldn't help but notice that it performs similarly to the Microsoft Surface Pro 2's usually lower-performance Core i5-4200U. True, the Surface Pro's processor is particularly well optimised for it, but still. One's an i7, the other's an i5. Enough said.
The 256 GB SSD allows the XPS 12 to start up and shut down in a mere 7 seconds, and programmes and apps launch super quickly.
The Intel HD Graphics 4400 graphics chipset (3DMark06: 5727) is even less powerful in the XPS 12 than in other laptops we've reviewed:
People don't usually buy ultrabooks to play heavy-duty video games on, but you still expect a certain amount of versatility when you're paying £1,000 for it. Here the only thing you can play are outdated titles and tablet-oriented games from the Windows Store. High definition videos, on the other hand, play without a hitch.
MOBILITY / BATTERY LIFE
Based on our tests (continuous video playback in airplane mode with headphones plugged in and the screen brightness at 100 cd/m²), the XPS 12 lasts 6 hours and 45 minutes, or a full work day. That puts it among the longest-lasting Windows-based laptop/tablet hybrids on the market.