Have anyone of you who dislike the game considered that it is your own preferences/abilities hindering or altering your judgement? Like if you are terrible at FPS, of course you won't like it. I don't understand how some of you think it is a "bad game" or that there was some corruption in the reviews. The last time this happened, it was against Halo 3. Everyone thought the game was "mediocre", but guess what? People are still playing it. And they will do the same with MW2.
If you don't like it, they who cares. If you suck at it, don't say the game is "unbalanced". It is in part your responsibility to balance the game with your own play skills. Like don't scream "camper noob" when you could easily huck a grenade on his ass.
Most people don't realize that the reviewers base their scores on "how fun it is" more than anything. That's why Mario Galaxy recieved such a high score even with outdated graphics and poor storytelling. Halo 3 was immensely fun with the same flaws (albiet in lesser quantities), and it rated highly because it was fun; it still has a strong fan base to prove it.
I don't understand the OP's gripes with the lobby. I find that it is the best I have ever seen. I don't have to wait to get in and start playing the game.
Also, most people don't leave when the lobby has a map they don't like. In some alternate universe people might hop off a lobby because they don't like a map from a game they just bought. I personally liked all the maps, as they each presented challenges to overcome, such as breaking through an enemy choke hold or storming a small cabin for control of the map.
And if you don't like the loss of peripherals, then turn up the sensitivity. I have it maxed out and I don't get jumped because I LOOK AROUND and PAY ATTENTION. If that blip that was your team mate disappears, that means he is dead. It is extremely easy to have a team mate watch your back and to pull the trigger before your get stabbed.