Absolutely love the X1 series. I use it as a daily driver running Linux and can vouch for some of the points made in this thread about them.
The gen7 had a screen malfunction, repaired under warranty with flawless service. I just upgraded because it would take two weeks for service turnaround, and we might as well have a spare laptop around.
Excellent keyboard, much better than Macs. I use trackpoint, so I'm unable to evaluate the trackpad. The internal display is 1920x1200, and I have nothing bad to say about it. Excellent linux driver coverage. Runs cool, even if it required capping its performance.