I've shot a glock lots of times and I like it but I ultimately went with the M&P because I like it more. I prefer the grip angle on the M&P, when I snap the gun up it's pointing at the target, not the ceiling like the glock. I find the M&P a nicer looking gun too and so far I've been impressed by the way it shoots and the quality, especially in a gun that cost at least 200$ less (around here).
Now, someone will definitely correct me if I'm wrong here but both guns are classified as DAO (double action only). My understanding of the glock system is that the striker is partially cocked by the racking of the slide and then you finish cocking it by pulling the trigger. While not being a true DAO, where you could just keep pulling the trigger on it's own to pull the striker, the trigger does pull the firing mechanism into place. The M&P, to me, feels more like a single action only. The stiker is entirely pulled by the slide racking (in fact, just the first quarter inch after the barrel disloges from the slide) and the trigger just releases the striker. Can anybody explain how they call that a DAO?
The trigger has the regular useless "give" where it does nothing, in it's travel and then locks noticeably into a sharp 6.5 lbs (or whatever) pull when it'll release the striker. You can really tell when the gun will go off, as with any pistol shooting on single action. I prefer that trigger pull myself.