Pretty good game,but weaker than Infinity Ward's work.
The main problems with this game are enemy vision and controls. By enemy vision i mean they can spot you before you spot them. This leads to you being fired upon and you can't even see the guy hitting you. More often than not,you just watch for muzzle flashes to fire upon. Then game forces you to try and use cover to advance,but it just doesn't feel right. This version has some controls issues such as collision detection,getting hung up in doors and on other objects. Overall,the game just doesn't seem as polished as the other CoD games. Still,the game is dirt cheap now and is worth playing for the $20 price tag.
Just don't expect the same level of greatness as CoD2.