The first time i played Modern Warfare 1, it wowed me. It didn't feel like i was playing a game but more like i was living it.
For example, like that scene where you are running off of the boat and the boat is rocking back and forth gives it realism.
SPOILER:
And at the end where you're almost dead and everything is in slow motion and you have to shoot the enemies with your last breathe of air. Best. Scene. Ever.
Just to add, the Chernobyl images were amazingly creepy, and the sniper level...omfg...was ground breaking. Although a great game, the MW2 campaign didn't have that same wow factor as you mentioned.
Modern Warfare 2 is better. If you are more into campaign then MW2 is better. If you tend to like multiplayer more than MW1 is the better bet. For MW2 there are quite a few upgrades to perks, and being able to choose your kill streak awards was a nice touch. But also if you just flat out are not good you get rewarded with a deth streak perk haha.
It's because of this game I don't ever get more than four hours of sleep a night - no joke, I seriously don't ever get more than four hours of sleep at night all b/c of this game.
For example, like that scene where you are running off of the boat and the boat is rocking back and forth gives it realism.
SPOILER:
And at the end where you're almost dead and everything is in slow motion and you have to shoot the enemies with your last breathe of air. Best. Scene. Ever.