This game is arguably the best FPS to ever hit the gaming community...
The story and experience of the campaign was uncharted. I had a lot of fun playing the story for the first month I had the game. At the time, the hype for the online experience was pretty limited. So it wasn't until January of the next year that I really saw the best side of the game--the intense multi-player. The leveling system, the customization of weapons and these things called "perks" just made the game unbelievable. It took me around 3 months of online play to reach the final prestige and yet I still couldn't stop. I didn't enjoy world at war so much (the guns were horrible) so now, 2 weeks before Modern Warfare 2's release, I am STILL playing the first, and enjoying every minute of it!!
If you haven't experienced this game yet, go up to game-stop or wherever and BUY THIS GAME!!!
...or of course you can wait two weeks until MW2 and enjoy everything great about the first one, along with many, many new awesome features...