I'm also on a X1 Carbon right now, got it only a month ago. Works great with Debian linux, although I compiled my own 3.7 kernel as the default 3.2 in debian had occasional lockups.

I wanted an ultrabook-style machine, i5, 4gb of ram, no cd/dvd drive, ssd only (no hybrid), decent screen res (1080p s a bit too big, 1600x900 is spot on), and most importantly a great keyboard. The x1 carbon was the only machine I could find that matched my specs, it has the best laptop keyboard I have ever had the pleasure of typing on. Highly recommend.

EDIT: The X1C has the first trackpad that I actually enjoy using, I usually have trouble due to sweaty hands, but so far this trackpad hasn't had a single problem and I have been able to get multitouch gestures working via synaptics.

If I had to think of negatives it would be the lack of ethernet/vga/hdmi without adapters, but at least they use 'standard' adapters (display port->hdmi, usb->ethernet).