Ya, Nvidia PhysX was highlighted like a new era of GPU computing power of Nvidia CUDA architecture. In reality, most of in game Physics Engines which runs on CPU like HAVOC, BULLET and their in-house implementation in different games (Crysis used a HAVOC based Physics Engine in original Crysis), can equal or better quality than PhysX. It is like making the game looking bad deliberately without PhysX and then bringing it to normal level by using PhysX, not what people think; Game is already good and PhysX will make it better.
Since I have a dedicated PhysX card, I observed different games with and without enabling PhysX and found out only in handful of them can actually get visually enhanced with PhysX enabled. Mafia II, Batman series are example of it whereas most of the games with PhysX implementation just doesn't show any real improvement. Also the Physics effects created by PhysX at its best is not at all anything superior to other engine, original Crysis, Half Life 2 Series, BF3 offer superior Physics quality with CPU bound Physics Engine.