I would want to hold one in my hands before making any decisions.
Read a review with concern about the trigger pull at 6.5lbs and a dislike of the trigger safety. These things are sort of something you will either be ok with or you won't. I am referring to the M&P40 because i couldn't find much on the M&P40L, not sure how much they differ.
All in all though, it will shoot as well as you do. Practice often. Try to not develop bad shooting habits. Put a couple thousand rounds through it and you will probably be good enough to hit anything your shooting at with it.