My wife and I both have M&P22s in addition to 9's and 40's. The 22s have been flawless. I did change the sights on mine and find a much prefer a fiber optic front sight.
My only caveat, and this probably only applies if you own both 22 and 9/40/45, is that you need to be "gentle" inserting the 22 mags, at least with 10 rounders. The 10 round 9/40 mags take a pretty good whack to get seated with a closed slide. If your muscle memory treats the 22 similarly with an open slide the top round will tip up. This is not a classic stovepipe; once the mag is inserted that top round will chamber just fine.
Not a problem for the shooting we're doing with the 22s: range, steel challenge and falling plates. These venues don't require mag changes.