Personally I haven’t. While Linux is imperfect, choosing the right distro makes the rest of the experience straightforward. And with it’s whole complexity, I find Linux more user friendly than Windows. Even driver issues, broken shadow file ownership and KDE specifics only made me more confident about my choice to use Linux after I solved everything.
Not on the kernel itself, just a minor bug that got fixed in the next release but could still choose the older kernel until then. OOM sounds like a bad idea when running out of memory - let the user chose what program to stop and handle it gracefully. Picking random process is bad. Others? DRM video at 1080p does not work on raspberry pi and it is not Linux fault really. Transition between X11 and Wayland took a long time to happen. Needed it earlier. Like before Ubuntu MIR. What impressed me is Linux and live cd. It is golden. Be able to surf the web while installing or just troubleshooting. Tiling Windows Manager and you can do whatever you want and customization.