I couldn't be happier with it - I have a larger laptop that I use as my "main" computer at home (essentially as if it were a desktop), and the XPS13 is what I take with me everywhere and use for presentations, developing on the go, etc.
I've used Linux as my main OS for some years now, and for me the main appeal of this computer was the size/weight/battery life when compared to my larger laptop. If you've been waiting for a Linux ultrabook for portable development (or even just ultra-portable general use), this is it.
Compared to my work computer (a Macbook Air), the difference is enormous. Hardware-wise, the XPS13 just feels slimmer, even though the difference in size/weight is negligible. The biggest physical differences are the keys and trackpad - I'm typing this now on a mechanical keyboard, and I've gotten so used to the Das Keyboard that I can't stand the feel of chiclet-style keys. However, the shape of the XPS13 keys (slightly indented) alleviates some of the annoyances I have with most laptop keyboards (the Air included). The trackpad is highly sensitive, and I like the texture slightly more than that of the Macbook Air.
Battery life is great, even with Bluetooth turned on (though I usually leave this off - I still haven't found a real use for Bluetooth on my computers!).
I should mention the display - it's the perfect size for me. I actually dislike the Macbook Air on this one point - it absolutely kills my eyes by the end of the day (both the default size and default brightness/contrast). I have neither of these problems with the XPS13, but it's still crisp enough that I don't feel like I'm missing anything.
Overall, I'm incredibly happy that I got it, and I actually get slightly annoyed now when I have to use my Macbook Air for work - I wish I could be using the XPS13 instead. Aside from the fact that I'd rather be using Linux any day, hands-down, the computer just feels more physically appealing in itself. Even at its price[1], it's worth every penny.
[1] I should note that I received my testing laptop at a 20% discount, though after using it, I would be willing to pay full price for it if I'd had to.