LAAG!! The release version of this game is buggy and destroys the MP experience.
I can only assume this is due to bugs or performance issues of the game software. Also the friends system in the game is totally useless. You can not form teams and there is no indicators for which players are your friends in-game. Making it very difficult to coordinate tactics.
Other than that new MP game modes are a lot of fun (when it works). But somehow the weapons in the game are somewhat irritating. Especially the sound design, which give the impression that you are wearing earplugs, as some sound frequencies (like metallic sounds) seams blocked out. This can be very irritating for audiophile players.
I dont know if GameSpot really has reviewed the PC version, but the QA dep. at Treyarch has defiantly not done their job here, and the games does NOT deserve a 9.0 at this point. Tray can potentially fix all these issues with patching but in the meanwhile MP is not worth playing.