The most annoying issue I've noticed is that copy and paste would stop working cross application sometimes (pretty poor). But turning off an "auto copy on select" option seems to fix that. Still an issue as its broken by default.
The laptop (AMD Matebook) is a different story. There is just not the hardware testing capacity that Microsoft and their hardware vendors provide. So kernel updates will break hibernate/sleep, or it has never worked. The trackpad will stop responding to taps after resuming, and other issues. There are also some minor graphical issues but that's mainly down to AMD drivers.
KDE is the best its ever been. The issues come from hardware issues that can never be fully tested and fixed without a vendor taking Linux support seriously.