I dont have any problems with it, but I think that Bullet is better (I dont know why I think that, but I do

).
IT looks like the open source model is winning once again..I havent seen anything important added to
PhysX for the last 2 years, and bullet seems very dynamic amd active. Ageia (Now NVidia) is more focused on promoting their
physics card, that no one knows about..it's a damn good idea, but it seems to go the betamax way, in other words, a lost cause. Anyway a major drawback is that you need to "install" PhysX..and when you upgrade to another version, you need to uninstall the old version first. So you need some kind of installer in your game, for both your game and PhysX. That was pretty annoying to me..
They have an installer but it's getting annoying for gamers that they have to install PhysX, then your game after.
I had to figure out what their installer did. It was just changing some values in the windows registry..then I made my own
installer that did that AND installed my OWN files as well..a lot of work just to get their physics engine going.
A top of that I also have to make a java binding...so here suddenly were talking 3-5 months extra dev time (spare time, that is)..and a lot of headache.
It would be easier without an installer, just a dll and a java binding..so thats why I'm considering changing to Bullet.
That, and because the Bullet demos looks better somehow.