I personally think the M & P 45 is an excellent firearm. I've owned two. I ended discovering I was a Glock guy. The high points of the M & P are excellent ergonomics, it fits more shooters than a G3 Glock 21 and it's a soft shooter. My biggest issues were fixable, cheap OEM sights (yep the Glock has them too), gritty trigger which I shot fine but could never get with, and poorly finished mags.
I ended up going with the Glock 21 G4 for a few reasons, better stock trigger, better mags with more capacity, and in my view it's a better finished gun. I also wanted to use the same platform for EDC and the Glock 30SF or 30s are both better concealed firearms. Having said all that, the M & P is a good gun, and if you get one you won't regret it, with a little work from a guy like Doug at ATE or Apex it can be a great gun.