Most people seem pretty pleased with them. For the number that are out there, I really don't see too many pop up on the local trading forum...so I assume M&P owners must be reasonably content.
If I add a hi-cap 9mm poly gun, it'll probably be one of these:
CZ SP01 Phantom. 18+1 capacity, CZ 75 ergos, and available for just a shade over $500. Didn't look to see if there's any LE/Homeland Security discounts.