We had about thirty or so in our armory. Looks like a fat plastic G3 grip without the barrel bundle, and like a pepperbox on steroids with the bundle.
Very quiet operation, not very accurate, and after the barrel pack is shot, you have to send it back to H&K for service and reloading. Oh, and it's a five-shot, not four.
All in all, a weapon with a very limited mission profile. I would have preferred if they had kitted us out with MP5SDs instead of spending that money on just enough P11s for one guy per LRRP team.