The thing about this PhysX stuff is that I never notice the difference until Nvidia actually points it out side-by-side in a video.
Even in the part where they were blowing away wall-tiles with a gun, it looked identical to me. I didn't even notice the debris on the floor until they zoomed in on it.
Seems like kind of a waste of GPU processing power, IMO.
Personally, I don't like the over the top physx effects in some games. The effects in Metro Last Light are subtle, but very good. I wish they would make the grenades deadlier though, like they were in Metro 2033.
The train scene which was featured in the 12 minute play through is a more impressive use of PhysX than anything seen in the Geforce video.