Maybe it's just me but I've owned 6 M&P's, I carry one daily, I shoot them in IDPA / USPSA and I am not easy on them and I have never had a part break. I clean them every so often, I make sure they are properly lubed and I run decent ammo.....
I understand that things can, and do, break but I think it is safe to say that the M&P line has the bugs work out of it at this point. If your buddy is having problems the first thing he should do is to contact Smith & Wesson and have it checked out.
Good luck and I am sorry to hear about his problems. Hopefully they can get it sorted out and he can enjoy the same level of reliability that the rest of us seem to enjoy.