I've migrated to Fedora KDE recently after having used Windows since childhood. Honestly it's not that bad. I mean, it's not good either - there are lots of random bugs or strange UI decisions - but all in all, it's not bad. I wouldn't install it on my mom's machine, but any tech-savvy person can use Fedora KDE with relative comfort. As in, the rough edges are there, but you won't hurt yourself if you know how to hold it.