i bought a M&P22 as a trainer to introduce my adult daughter to handguns. Generally I think the M&P22 is pretty good in that role. It's not too intimidating as far as blast and recoil. But, with the moving slide there is enough recoil to let a new shooter get an idea of what to expect with a full sized service pistol. Also, for a beginner who is just experiencing a trigger, the trigger is forgiving. However, I don't own another M&P so I can't compare triggers. I do know there is a world of difference between the M&P22 and the triggers on my S&W revolvers or my Norinco 1911 (which has an excellent trigger by the way).
That said, I use the M&P22 for my own training to concentrate on sight acquisition and follow up shots. While the M&P22 trigger has a lot of take up compared to my other handguns, I adjust in very short order. -- and you really can't beat 22lr as far as training round.