PhysX is used in many games, no question.
It is however more used in games where it is more of a gimmick (i.e. smoke, clothes etc) and where accuracy is of second importance.
Major players like Skyrim etc use Havok.
I also found this nice review: Havok is used a little less htan PhysX, but in the ‘excellent’ games department it is used much more.
That being said, if I was about to do a game where physics is a gimmick and budget is stringent, I would also use PhysX.