I've had a Dell XPS 12 to play with for some time now. Let me share my thoughts on this hybrid Ultrabook.
As a user of a Macbook Air 13-inch, I am intimately familiar with the Ultrabook form factor, since most PC manufacturers realized there was a market for these beasts when the Air sold like crazy.
The Dell XPS 12 running Windows 8 is not exactly the thinnest and lightest Ultrabook out there (it is 1.54kg to the MBA's 1.35kg) but it does include a flippable touchscreen that makes it into a tablet. In real world terms, an XPS 12 is lighter if you carry a MacBook Air and an iPad together.
Here are the specs of my stock model, priced at S$1,899
Processor: 3rd Generation Intel® Core™ i5-3317U Processor (3M Cache, up to 2.6 GHz, TPM)
OS: Windows 8 Pro, English (64bit)
Display: 12.5 inch LED Backlit Touch Display with True Life and FHD resolution (1920 x 1080)
Memory: 4GB Dual-channel DDR3 (soldered on-board)
Storage: 128GB Solid State Drive
Graphics Card: Intel® HD Graphics 4000
The screen is where the Dell XPS 12 shines. Even though it is slightly smaller at 12.5 inches to the MBA's 13.3-inch screen, it is full HD at 1920 x 1080 compared to the 1440 x 900 on the MBA. That's quite a lot more pixels. And it is Gorilla glass.
At first glance, the frame of the XPS 12 and it's flippin' screen (sounds so wrong) looks flimsy but after using it a bit, the construction feels robust.
I spend a lot of time with input devices, writing and editing, and the keyboard feel is nice but I wasn't fond of the trackpad. The touchscreen felt responsive though, which is great if you are a heavy tablet-form-factor user, not so great if you are a laptop-form-factor user.
I enjoyed using it in the tablet format. But sometimes the Windows 8 OS throws me off. At 12.5 inches, the screen is great for watching movies in full glorious HD and surfing but again, recently I've started migrating from my full-sized 10-inch iPad to my iPad mini more. So it depends on how you use tablets, really. At this size and weight, the XPS 12 is not a tablet you can hold with one hand in the MRT train. But it is cool to watch movies off it on a plane.
Performance and battery life is about what you'd expect out of an Ultrabook/Macbook with these specs. As a tablet, it blows the ATOM and ARM-based tablets out of the water since it is running a 3rd-gen Intel i5 processor inside.
The XPS 12 does not have a Ethernet port but you can add one via USB if you wish. The wifi is Dual-band 2x2 which is serviceable, though I wish it were the faster 3x3 kind as we need more and more bandwidth. I'd buy a USB Ethernet adapter for those days when you are able to use a wired network connection.
I'd say the XPS 12 is a good buy if you are looking for a single replacement for your laptop and tablet needs. It isn't the thinnest, lightest and fastest ultra-thin laptop or tablet out there, but as a hybrid, it does pretty well. For what Microsoft is asking for a Surface Pro and keyboard (sold separately), you may be better served by the XPS 12, especially if you don't need the Surface's strength with pen-based input.
Go ahead, take the Dell XPS 12 out for a spin, or more accurately, for a flip.