I don't know exactly. Maybe I'm spoiled with shooting the Mk23 Socom fairly often, but the M+P seems so "blah". It doesn't do ANYTHING exceptionally well at all, and I'd say it's average at best in most categories.
1: The trigger is a JOKE. And I've got a free-state gun with none of the nanny state BS on it. Mine tested out at 7 pounds, which is not the worst by any means, but it's a bad 7 pounds: scratchy, rough inconsistent pull with a long reset and no "feeling" whatsoever.
2: I don't like the way it points. I've got two Glocks as well (which I like) so I'm not one of those "plastic guns are soulless, grip angles wrong blah blah blah" types. I just don't dig it.
3: It feels "unrefined". It's the same feeling I get when I sit in a late model Camaro (No offense intended to Camaro drivers here). It says to me: "I was built with no particular shining attributes, I'm not particularly good at anything, I don't entirely suck but I'm not gonna win any awards either, and there's a bunch of products for a little more money that blow me out of the water."
I know that some folks really like theirs, and I don't like to pee in people's Wheaties, so when a discussion comes up I either keep my mouth shut or say something like "I don't dig mine, anyone want it?".
I don't dig mine, anyone want it?