I have to say without reservation that Modern Warfare 2 is the best single player experience I've ever had in a video game ever. This game is unbelievable. I've never seen such an amazing and engaging game. That airport level was seriously intense. It took a second to even register what was going on, and then replaying it a bunch of times to try and figure out if there's a way out of the moral quandary.
The multiplayer game is spectacularly done too. I can't say I've played a lot of that yet though. What I have played has also been first rate and I plan on spending a lot more time playing it.
Congrats to the team at Infinity Ward on a job well done. They've set the bar very high.