Best online!
The online play is good with no lag that I have experienced. On some occasions the game does bog down from very graphically intense fights, but that only last a second or two.
The graphics....wow the graphics...there isn't much to say about it other than the screenshots don't do any justice to the game.
The sound isn't as good as it should be. The gun fights are very repetitive but you don't even notice it after a while...I'm not playing with 5.1 so I'm sure its not nearly as bad as just coming from 2 speakers. The music on the other hand is extremely well done and it sinks you deep into the game where you almost think you are in the game. If I could break sound down to music and sound effects, I would give music a 8 and sound effects a 6.
The only bad things I dislike about the game are that there's no bots in darkops mode, little trash talking punks with their squeaky voices (but I guess Rare couldn't do much about that), the multiplayer games sometimes seem a bit too slow paced for what Rare seemed to be aiming for but that depends on the map.