I am now 70% complete, haven't finished the main story but have done quite a few of the side missions, although I'm not looking forward to trying to unlock the final part of the Riddler chain.
Performance for me has been fine, running at 4k with no AA or gameworks turned on the framerate has been a solid 60 regardless of what's going on.
The only glitch has been one point where the batmobile turned invisible for a few minutes.
At the start of the game it felt like the batmobile was being rammed down my throat every 2 seconds, and I have found that I am enjoying the game a lot more by not using it to get around the city, only when you actually HAVE to use it.
My only real complaint is that the boss battles so far seem a bit lacking, the great storyline makes up for it.