I grew up with S&W revolvers and the S&W name has always held a special place in my heart. However; I never cared for their Gen I-III semi autos because I wasn't comfortable shooting them, and they didn't develop a good reputation for reliability during the 1980s as compared to Beretta back then. I read about the M&P when it was first introduced, but didn't actually get to shoot one until I was training with a department that was hardcore S&W through and through despite all the issues they'd had with their standard guns, the Sigmas, and the Walther collaboration pistols. They had converted to M&P 40s, and I had a chance to put 50 rounds through it. The officer who loaned me his pistol warned me that the trigger reset was pretty vague. I was pretty die-hard Glock at the time, but had to admit that my follow-through was quicker with the M&P, and I didn't find the reset, or rather supposed lack of to be noticeable.
About a year later, the bunch I work for authorized them as a personally owned option and I bought a full size 45. Of all the pistols I have owned, the 45 probably has the third highest round count - behind my Gen 1 Glock 17 and a Glock 27. I have experienced a problems with it a time or two, but it never malfunctioned during the first 6000 rounds, and that was because the recoil and magazine springs got tired. I have had the same issues with Glocks. The striker recently broke with just over 7K rounds, but I've also had or seen Glock parts break the catastrophically enough to put the gun out of action requiring armorer service. S&W's warranty service has been excellent.
What I like about the M&P over the Glock or Sigs is the ergonomics and the fact that the trigger face is smooth and not serrated. I also like that the S&W points more naturally than the Glock - the Glock tends to point a degree higher. I have had a couple of Glock 21s which were reliable, but less comfortable to carry concealed than the M&P 45 full size. I double I had more than 4K rounds through the first, and probably 1500 through the second, so I never got to the point where parts would start wearing out.
I recently acquired an M&P 9, which will replace the 45 as every day carry. The reason only being that arthritis is starting to set in and a prolong range session with 45 ACP stirs it up. Still, the full sized M&P 45 is a lot more friendly to shoot than the Glock 40s, in my opinion.
Wonder if I'll get "likes" or "dislikes" to that last statement. 
