What people really should be banging about is that it's not only used as a selling point, but also (And much more effectively) as market extortion. Nvidia gives developers money, top level support, and bucketloads of Nvidia cards to put in dev machines, as long as they include certain specific instruction sets and run their middleware.
Then when the games that could potentially be freakin awesome come out, we're getting a message from nvidia reading, "Buy our Cards or your game is going to suck". Mafia 2 is a prime example (Granted it sucked anyways, but that's another story).
This sucks for everyone, not just ATI users. Not because you get to play the game with higher frames than we do because of proprietary middleware, but because as long as the industry is divided on physics, it will never advance in that aspect.
I have a 9800GT that works perfectly with the hacked drivers to get it working along side my crossfired ATI cards. So really the only thing bad I get out of the deal is a higher power bill (I leave it out because of this). But idealistically, I want nothing to do with PhysX, just simply because of what it stands for. There are so many comparable alternatives, it just makes no sense to use it, outside of selling out.