I didn't exerience the game killing mainline questbug.

I did experience the save game seems to have disappeared bug but after installing the game on Windows 8.1, I copied my save games over and they were fine. Had no problems with save games since.

I was having problems with Uplay glitches and synching my save games failed every time. This all went away with Windows 8.1.

I didn't have any issues with spamming and phishing.