Modern Warfare 2 takes players to the snow-capped peaks of Russian mountains, across the deserts of Afghanistan and into the streets of Rio de Janeiro, and introduces a new co-operative Special Forces mode to back up the single-player campaign.
Graphics may not have been best for the time of release, but well-made graphics design compensates that a lot.
Best sound design ever in CoD history. Weapons have unique sounds (unlike almost every other CoD game that came out later), and this is last CoD with soundtrack composed by Hans Zimmer - back in the days Activision put more into music than into marketing...
No more unlimited respawn in singleplayer (CoD4, you lose this point).
Cons: no server browsers, hackers on servers, no mod support, Activision shuts down FourDeltaOne (why be a ****? The game was several years old - let it be!)