I recently shot the P22, SR22, and M&P22 back to back. The P22 and SR22 are not full size guns. The M&P22 is. The grip is exactly the same size as a full size centerfire M&P with the medium grip insert. The differenyes are a bit less weight, a better trigger, and a 4.1" barrel instead of 4.25". The M&P22 will definitely be my next handgun and it seems very accurate to me. I was indoors with the kids so the target was only at 7.5 yards iirc, but the first 6 shots went into the same hole shooting freehand with Winchester bulk ammo.
"Those who would give up essential liberty to purchase a little temporary safety, deserve neither liberty nor safety."
- Benjamin Franklin