I carry an M&P 45.
Some of the early M&P production runs had problems: trigger issues, rust issues, and a few other weird gremlins that have mostly been worked out. If you've put a few hundred rounds through, and aren't having failures to load or failures to fire, you should be ok. And if your slide isn't rusting, then you should be ok on that front too.
Some folks think the trigger is too gritty or too heavy, and get trigger jobs done or aftermarket trigger kits installed. Personally, I think that's a bad idea unless you're having problems or are using it as a competition gun. If you opt for a trigger job, take it to the BEST gunsmith you can find, or contact S&W to have the work done.
I find that mine can be a bit of a pain to conceal, but depends on what I'm wearing.
All in all, good choice of firearm.