I bought it only because of the single player, it looked really good, but I just got stuck with the multiplayer lol.
War is the only mode I play, the frontline moves and there are targets to achieve, which require team work. This is good. What is bad, is the general COD attitude against other players in the chatbox, if someone kills you (some people expect not to be killed in the shooter) or if someone ends up in the losing side (the team gets instructions to uninstall the game etc).
The other game modes are unplayable, I should be in my early 20s to cope there and I'm not sure if it would help me anyways