Imho i could not really tell that much difference between the console and pc versions of arkham asylum except for maybe the antialiasing and anisotropic filtering, even then not much in it i thought.
Me, i'm purchasing the pc version of arkham city because of nvidia 3d vision + physX, therefore Nvidia TWIMTBP .
Huge differences with PhysX as well as the much better looking graphics make Arkham Asylum look a LOT better on PC!