Now the big N is behind it PhysX is getting a lot more support from developers but I've not yet seen or played a game where it has proved it's worth.
One thing I have learned from all these "advanced tech" is that developers adopt what is applicable to most systems. PhysX may provide insane performance improvements but requires nVidia cards which is a deal breaker compared to Havok. That is where they shine, as Havok's physics could run on any computer with a cpu (which computer doesn't
This behavior is understandable as developers need to learn only one thing but it applies to more systems (less work, more gain).