I own a P22, OD frame black slide. I have no clue where the hate comes from... mine has seen over 5,000 rounds of Federal ammo. I have had three failures in 5,000 rounds, two due to the first round in the magazine popping up when slapped in hard, both failures from the same magazine, and one fail to fire after many re-strikes (bad round). I own 5 factory magazines for my P22, too.
The P22 has a better trigger than the Mosquito as well as cheaper magazines, and the ability to change back and forth between barrel lengths easily, plus the ambi mag release. I love Sig stuff, I own two 226 pistols, but I am not a fan of the Mosquito. To each his own.
I did not consider a Mk II or III, not because they are bad guns, but because they are heavy bricks with non-standard controls (mag release, safety, etc). I would like to own one one day, though, because they are very nice pistols. Plus, the sights on the Mk II kick the ass of Mosquito and P22 sights any day.
For anyone complaining about the zinc slide... get over it. Polymer framed pistols were inferior pieces of junk that got weak in the sun 30 years ago and the opinion was that they were all crap. The early P22s had problems with slide cracks due to the way the slide was produced, just like early polymers were more sensitive to UV light. Technology improves.
The P22 does have a steel breech block, by the way.