I'm not big into multi-player, so is it worth it to buy the game for the single player campaign?
there isn't any single player, however, the multiplayer is fantastic. I always play the realistic servers and the atmosphere is fantastic, the music as well as the in game effects (such as supression) really make you feel like an american soldier assaulting Iwo Jima or a Japanese soldier rushing American lines at Guadal Canal. This game feels more authentic than most other shooters and that's why I love it. You can always play on servers with bots if you don't like playing other players, however you wont get as much of a challenge from them. Another key aspect to this game is that teamwork is required to win. One of the more popular game mode is territories, which is where one team attacks and has to capture multiple flags (usually 1 or 2 at a time, 5-6 total typically) in order to win. If you are attacking coordinating the various player roles is key to ensuring a succesful assault, otherwise everyone on your team will be destroyed piece meal by the defenders machine gun emplacements/bunkers. Personally I enjoy the challenge and don't mind dying as an attacker. As a defender most maps offer great spots to mow down attackers, so either way it's lots of fun.