This game is overrated. It does not have the best multiplayer.
Cons - Story mode is too easy, graphics are poor compared to other games on the 360, other gamers are rude on multiplayer, not a lot of variety in the level design
World at War is a very easy simple game. I am a mediocre gamer. Most of the time medium setting can be difficult for me to complete in most games. However I was able to beat veteran in this game in just one sitting. The trailers made this game look like it would have some of the best graphics ever seen on the 360. I was sadly mistaken. The graphics are piss poor. Many gamers rave about the multiplayer. I believe that Battlefield: Bad Company has a much better multiplayer setting. In World at War the maps have generally the same layout and the other gamers you will play with do not work as a team. Most are out for themselves and just gaining points for themselves.
However this game is somewhat fun. Multiplayer does have a lot of game modes to try out. The return to World War II is surprisingly refreshing. Even though the story mode was simple, it was very enjoying bayoneting Nazi's and lighting Japanese on fire. That leads to my final point. World at War introduced two new weapons. The flamethrower, which is one of the coolest weapons the video game world has seen (however it is overpowered) and the bayonet.
Bottom Line - A pretty fun game, but if you do not have it you are not missing anything.