MW2 is one of the most successful games of all time, strange to see people talking so much shit on it. I never really got into it but I know a ton of people who play it religiously and it looks pretty fun.
The primary reason so many people are talking shit about it is because they're PC gamers. PC gamers were royally screwed with MW2 by the IW developers, because the PC version was a direct port from console.
1. No dedicated servers (p2p instead which is far inferior in terms of connection)
2. No server browser. A POS system that chooses who you get to play with. Nothing is more irritating than when you don't want to play with certain people, you leave the server, then try to join a new game and they stick you right back with the same group of people. + You can't choose which map you wanna play, can't sort shit, just sucks..
3. You can't vote kick people..
4. No admins who can kick cheaters..
5. Can't switch teams, autobalance doesn't work.
6. No dedicated servers means no special gameplay enforced rules like Tactical Realism (which is what I played exclusively in prior COD games), and no automated kicking for shit like early nade/explosive spamming.
All that being said, the actual gameplay itself is great. I've racked up near 300 hrs myself..