Umm... not much to be honest. It's overall pretty great. I switched my main rig fully to Linux about 2 years ago.
First year was Manjaro w/xfce which got a little janky around the edges, probably due to how they avoid using the AUR directly. Can't remember specific problems that couldn't be attributed to old RAM or my own tomfoolery.
Past year has been on EndeavorOS w/KDE Plasma. Took a little time on the Arch wiki to get my Mesa install fully operational, but wasn't bad. And I think at one point yay tried to compile electron32 from scratch which was kind of insane (probably wasted 80 GB of download for that one night) but eventually I found forum posts saying it was fine to just remove. Besides that, it's been fantastic. It's rare now that I even find a game that doesn't work well, and half the time I forget to even check protondb like I used to.
Oh here. I guess combining PDFs could be a better experience. Had to use pdfunite in the command line which worked well but felt a lot more awkward than just using Acrobat to drop in pages and rearrange them. But there's probably a GUI utility I just didn't find.
Ah, and printer support. Wifi printing worked once for no apparent reason then never again. But printers are terrible in Windows too so I blame the OEMs.