my M&P .40 is a dream to shoot. It's the only pistol that I can shoot 1 ragged hole with all day long, and it's the softest recoiling .40 I've ever shot. that being said, mine has had some serious problems. after about 600 rounds, the slide developed a crack on the bottom slide rail. not a ding or a chip, but an actual stress crack! I've never seen anything like it on a pistol, and I've only shot tame factory ammo out of it. Luckily, Smith&Wesson took care of it no problem - replaced the slide for free, and pretty quickly too. love their warranty!
then, about 1000 rounds later, it started developing a problem that would cause the magazine to eject after every few shots. NOT the kind of problem you would want to happen when you really needed it. sometimes it would just release the magazine about a inch, sometimes it would actually eject the magazine all the way out, onto the ground. so now it's being packed up for it's second trip to smith & wesson.
the bottom line is that if I had these problems with any other pistol, it would be sold within a week. however, I am so accurate with this gun and it feels so good to shoot it, I decided to keep it and get it repaired again. I'm one of the few who's even had problems with their M&P at all.