When standing completely still.
I won't accept any other arguments of other games; the likes of TLoU, Crysis, Uncharted, blah blah blah.
When Unity is at a complete stand still (freeze or just not moving) the game is so vividly detailed it's almost unbelievable.
Just recently finished it and I stand by this statement. The game itself underwhelmed me the more I played. There is just way too much to do. The series needs to be simplified and turned back into a video game.
I I had no desire to 100% Unity like I did twice (PS3 and 360) with AC2.
But it I digress. If Unity ran smoother it'd be the prettiest game ever in motion. As it is, it's the prettiest screenshots of a game.