I got the Carbon X1 Touch myself, and absolutely love it. I only have two complaints:
(1) my battery only lasts for 2.5 hours in linux on a good day, while it lasts over 6 hours in windows, and
(2) I develop touch-based apps, and ubuntu doesn't broadcast touch events to its browser. The system itself can receive touch events (if you tap three fingers on a window, it triggers the move mode), but the browsers themselves only receive mouse events. The result is that I cannot use pinch-and-zoom on touch-enabled webapps.
I had similar problems with battery life. Take a look at TLP [1] - my battery life improved dramatically after installing it (mostly on default settings).
(1) my battery only lasts for 2.5 hours in linux on a good day, while it lasts over 6 hours in windows, and
(2) I develop touch-based apps, and ubuntu doesn't broadcast touch events to its browser. The system itself can receive touch events (if you tap three fingers on a window, it triggers the move mode), but the browsers themselves only receive mouse events. The result is that I cannot use pinch-and-zoom on touch-enabled webapps.