to be honest when i palyed the beta, it seemed (this is on power struggle) there was nothing to encourage you to work as a team, this lead to either a really easy game just larking about while others killed (or hacked) others for easy points, they get the tac tank, game over rinse repeat..
i don't know if it's different in the proper MP i haven't had a proper chance with that yet.
I tried the instant action earlier and to be completely honest its manic. weapons are spread out which is fine, but theres always one person who finds the biggest gun and camps atop a tower and kills all who spawn..
also you do end up spawning RIGHT in the middle of some serious fights, either getting you insta killed, or allowing you to pistol whip 2 people pretty easily.
its pretty intensively low on the fps i found, so if you're in a fire fight. and someone switches to maximum strength and you have to flick around to find them it jsut blurs and makes it impossible, often resulting in them belting you and you dying..
also spawning to see some random red glowing dude running around then you die as he's punched you lol.
but as i said i haven't even seen any of the advanced vehicles or vtols or choppers in the multiplayer yet :S i don't think i've been on a map that can have em yet. but it does seem like once one person dominates, its pretty much game over for the other team.
not an in depth review but from what i played it doesn't seem to promote team play well enough in the power struggle, and instant action seems to be lacking tbh.
its fun but i wouldn't compare it to the likes of cs or bf where teamplay is kinda vital to success. and i haven't played cod 4 yet so i can't comment on that.
hope thats helpful, sorry if it makes no sense i'm a little tired but thought i'd post before i forget and end up not posting at all lol.