Check Rimfirecentral.com for lots of info on the P22. If buying used, be aware that early models may have has some teething issues, as reported on that site. If new, then all should be good. Interesting reading none the less.
I have one, short barrel. It is fun to shoot, but feels small in my hand. Seems well made, especially considering the $$, but I do not have more than 500 rnds thru my example to give any insight on longevity, etc.
Also check out SIGs new Mosquito. It is also a .22lr semi-auto designed after their P226, but at reduced overall size. It should be (I dont think any have shipped from the Mfg yet) quite a bit larger than the P22, which is quite small. If this one has typical SIG quality, then it should be a winner.
I love all .22s, and if I wasnt saving for a S&W 41, I would be looking at the new SIG.