After posting in this thread, I spent a good solid 2 hours playing the game.
It's fantastic!
And the PhysX stuff adds a lot to the game. I am sure the game would be great without, but just seeing how Batmans cape moves as you walk, and wrinkles in a different way based on your direction, or how things on the ground will kick up as you move past, just ads to the ambiance.
I am no game reviewer, there are plenty of those out there, but it's just a really fun, very moody game. Play it in the dark with the sound on and you get a real feel of being in that old place, with all those crazies around!