... Metro 2033 is a tad over a year old, Mafia 2 is not even a year old, and not even Batman AA is quite 2 years old yet... yes clearly outdated.
I'm not hung up on PhysX or anything, but it sure does make Mafia 2 a lot nicer - so many bits of debris flying everywhere during fire fights makes it notably more fun, especially in 3D. And no, AMD doesn't have a real 3D solution and the driver support isn't even in the same ballpark using iZ3D. For a fee you can walk into the shop, get it, come home and be playing in 3D within minutes - there is no ATiMD option for that.
If you want bang for the buck and a lot of driver hassle and enjoy almost universally poor multi-card support then I can see the appeal of ATi - bang for the buck is the biggest selling feature for the indiscriminate gamer