If Unity wasn't bugged as hell, I will be damned if it wasn't one of the best AC games ever made. If you just for a second forget about bugs and stuff and go clear of its initial skin, the game was a f**king masterpiece. No other game in the series ever made you feel more as Assassin (Specially the new ones) and allowed killing in disguise as compared to unity.
I'm currently trying to beat the game, there were lots of visual issues, Inverse kinematics bugs, ragdoll bugs, etc. This is the first AC game I've played tho, so I might not know if the previous games have the same issues