Keep in mind: much of what I mention the below is done on purpose by design by the Gnome project, and aren’t necessarily bugs per se.
When Gnome 3 was released I pretty much immediately took the plunge and upgraded to it. I initially used the default Gnome Shell for a bit. There were some really big regressions right away. You can’t change your fonts, icon theme, GTK theme… I found a tool called gnome-tweak-tool that does allow changing those things, but I find it annoying that I can’t do it via the default system-settings tool. ....
Then there’s the screensaver.....