I purchased it 2 years ago and would fire 100 rounds per month of Winchester white box ammo with about 4 handgun courses intersperced where I fired between 200-300 rounds each. About 200 rounds of Remington golden sabers to make sure they would work fine before I started carrying them.
So a bit over 3000 rounds so far. I've had zero malfunctions so far. If I can find my camera when I get home I'll upload photos.
For the moment though, the wikipedia page has a couple nice pictures:
http://en.wikipedia.org/wiki/Px4
As an aside, I've stopped going to the range monthly and I'm sticking to dry firing and airsoft (don't laugh) for the majority of my practice. Hopefully when the run on guns and ammo slows down I'll be able to go shoot again.
EDIT: I just realized the wiki page has a list of some departments that now use the Px4. You may be able to contact them to get their take on the weapon as well.
EDIT2: My roommate "borrowed" my camera. Pictures will have to wait for another day.