Batman: PhysX Origins
You probably know Batman. He also had a few good games made about him. And the upcoming Batman: Arkham Origins will find a new convoluted plot to make Bats chase festive criminals around the city. And you best do it with PhysX!
The video above shows how Arkham Origins looks with and without PhysX. While the engine itself doesn't do anything major (say, destructible environments), it does serve to breathe life into the world. Or fog. Boy, do they love themselves some fog and fog effects. You probably won't miss them if your PC can't do PhysX, but the Nvidia crowd will probably notice it.
It's not only fog, though. You gonna get softer shadows the further you are from a light source, falling snow, actual dynamic footprints in snow...and a warp effect on what I assume is a Bat-Powerfist (somewhere, a Games Workshop exec is crying because he can't sue for that).
So, is your PC up to snuff? Can it run PhysX? Do you really, really notice it?