I have a first gen X1 Carbon and love it. It does have the usual downsides of most ultrabooks; soldered on ram and non-standard drive, but has been rock solid. It has a chiclet style keyboard, trackpoint, 3 physical mouse buttons, 1400x900 resolution on a 14" screen, on a machine that's basically the size of a MacBook Air 13". Linux just works out of the box.
I know that the X240 series are still "proper" ThinkPads in that they are easily serviceable and use standard RAM and drives, but have no personal experience with them.
Good luck!
-jason