I own both the MKIII and the P22 and I like the P22 much better, not to mention that Ruger is a bear trying to get back together after taking it down to clean it. I may be letting my bias show as Walther is #1 in my heart. I own a P38, P99, PPK, and the P22 and all are superb guns in my opinion. Love those Walther'sI was not really surprised at the outcome of that comparison, I had a Ruger, and it was an OK gun but I like the P-22 a lot better.
I read some posts about using a P-22 for home defense over at RFC, it got quite a few laughs over there. Trust me a 22 LR round should get more respect than it does. I keep one under the pillow at night and sleep real well.
No, I am not saying that it is the ideal defense weapon for everyone, just saying that is what I use at present.