I'm using an X1 Carbon Gen 11, and for my purposes at least, it's an improvement over every previous generation.
I'd love to switch to a Framework one day, but I'm not willing to use a laptop without mouse buttons. (I don't care about the TrackPoint at all; I do care about having physical mouse buttons.)
1. The laptop overheats easily. It is usually hot to the point of being painful to touch. It has melted the adhesive of the rubber strip on the bottom, which has fallen off.
2. The trackpoint is malfunctioning. Several times a day, the mouse cursor will jump to the top of the screen, and be stuck there until I wiggle the trackpoint fully in all directions.
3. There's coil whine and clicking from some part of the power intake.
4. Battery life is extremely poor, usually on the order of ~2 hours.
5. Sometimes the trackpad buttons will stop working. You have to put the laptop to sleep and wake it up again to get them back.
6. Plenty of random freezes and black screens.