I used to like MW2. I can still play it now, and not have too much of a problem. I try to like it. But damn, it pushes me away, almost deliberately.
For the record, I have the 360 version (my condolences to the PC players. I know that version got screwed over)
I actually kinda liked the campaign. Not as good as CoD4 in some aspects, but I still think it did some things right. Not as realistic, but realism isn't what I'm all about, and it's not what games should be about (at least, not all the time)
The multiplayer has some pretty bad faults though. Its core is fine: it has good controls, most of the weapons are pretty good, the new perks were pretty nice, and I liked weapon customization. Up until that point, I find it to be a perfectly good, responsive twitch shooter.
It's the additions that are bad. Some of the equipment is really unpleasant (claymores can be downright gamebreaking, I've witnessed firsthand), they absolutely messed up the killstreak system, which I was only so fond of in the first game anyway. The whole chopper/gunship/nuke thing sounds great in paper, and is awesome if you get it, but if you take it objectively, ITS A TERRIBLE IDEA! If someone is able to get that many kills, why give them more killing ability? And the killstreaks are very much overpowered, especially that chopper gunner. Akimbo wasn't a terrible idea for some weapons, except for shotguns. That was a terrible idea.
A lot of these gameplay features could be tweaked and made to work, though I haven't heard of IW doing this before, and it looks like they won't get a chance now.
But I can live with bad gameplay decisions. Most games make some, at least.
What really pisses me off is the community. They are rude, racist, exploitive bastards. The last time I remember playing MW2, which was a while ago, was when this kid got angry at me for messing up his supply drop glitch. I literally exploded on him, and usually I don't talk much at all on games. Since then, I haven't been able to get over my disgust with the community, though this is hardly exclusive to MW2.
So, in review. I don't hate this game. I actually used to be very fond of it. I just can't stand it any more.