I am playing with EVERYTHING on max,have a 560ti 448 core @ 1920x1080 last night.
Only time I got even a slight bit of slowdown when I had maybe 10+ enemy bodies in the floor infront of me. Think this is to do with the physx, but the game runs shockingly well!!! Looks stunning as well. I won't be tinkering, I am perfectly happy with it.
As for the game, wow... Just wow, I am truly sucked into this, was up until far too late last night, playing Zer0. Got to level 7, feel a little weak, but judging by the talents, I will be for a while, playing the assassin skill tree. Absolutely awsome lol.
What version nvidia drivers are you running agnes?