Just upgraded today, already regretting it. I have terrible VSync/tearing problems. Before it worked flawlessly.
I already tried all compositor settings, some of them seemed to temporarily remove tearing, but after about a minute I could notice it again.
In addition to that I can't enter my full-disk-encryption password when it starts the GUI version, only when I reset the PC and it starts the fallback CLI version.
GPU: GTX 780
CPU: i7 4790k
Screens: 3x 1080p (DVI-I + DVI-D + DP -> DVI)
Driver: Latest Proprietary Nvidia Driver (just updated today after upgrading)