I think it's the best game that I've played for ages.
It's slightly different to what I was hoping for/expecting... It's still amazing, but just in different ways.
The single player is 10x better than CoD2's, which doesn't even have a sprint, has totally obvious (and often annoying) grenade spam trigger points and the oft mentioned infinitely respawning enemies.
There's a huge variety of weapons and attachments to use along the way, which are about 100,000,000,000x better than the send-you-to-sleep-boring MP40's that must be the most over used thing in the world of games since the exploding barrel!
The environments are about as open as you're going to get in a game with so many cinematic scripted events, rather than the corridor after corridor of previous games, meaning that you could probably replay it dozens of times, taking a completely different route, seeing different parts of the environment and shooting different enemies each time.
It's interesting, as just before MW2 came out I was going through HL2 Ep1, and it really brought home the on-rails nature of most FPS campaigns. You can't go left, you can't go right, you're just shoved in a direction, and have to shoot the same old enemies over and over again, with maybe a simplistic puzzle thrown in to mix things up.
I also went through CoD4's campaign recently, while I was waiting for my internet to get connected, and while it's a top rate campaign, it's by no means better that MW2's. Not by a long stretch.
I've been through the MW2 campaign twice. Once on Hardened and once on Veteran, and I enjoyed almost every bit of it both times.
Special Ops is amazing, and even though I've put over 5 hours into the MP, I still feel like I've barely scratched the surface in terms of it's depth.
I mean seriously... The MP is DEEP, and I can see it staying enjoyable for the next two years.
All in all, I don't know what people expect when they play this game. It's delivered the quality that I expected, although not through the means that I was expecting.
Although, having said all of that, if you enjoyed the utterly AWFUL MOH:Airborne, then your taste in FPS's is certainly not something that I can understand.
(0 wins from 17 games made me laugh, btw!)