I own a P22 3.5" and like it. My wife really likes it. It is an accurate shooter and in my experience does good to around 200 rounds before it REALLY needs cleaned. The action gunks up pretty quick and will quit cycling. If you keep it clean, it's a blast to shoot. I had trouble initially with it (probably didn't clean it well enough when it was new) but once I had the factory grease out of it, it runs great. I would have to say that I am personally eyeing a Ruger 22/45 mark II or mark III. I have seen one of those run 3 full bricks during a range session with NO MALFUNCTIONS OF ANY KIND! I wish my P22 would do that! Like I said, about 200 rounds is all I get before it gunks up and I start having problems. It's not hard to clean, I just sometimes have to do it at the range to be able to keep shooting. I started out using CCI Stingers and now just use the cheap-o brick ammo. I haven't found any ammo that gives me trouble feeding or cycling in the gun and all seem accurate. I regularly shoot pop cans at 50 yards with it (probably 8 hits with a mag of 10 rounds).
I like the P22 and don't plan on getting rid of it. I am however looking at the Ruger as I said, maybe just for something different, but also because I saw one go over 1500 rounds in one afternoon with no cleaning. That impressed me.