Overall, World at War is a very good game. If you are looking to play multiplayer, be wary; it can be very unbalanced. You will find that using a bolt-action rifle proves to be pretty useless when everybody else is using machine guns. However, if you can find the right server that you enjoy, WaW can provide hours of entertainment. Also, the single player and Nazi Zombie game modes are superb. In the end, I would recommend giving it a try.
just to add.
cod4 with WWII skins/maps/weapons.
World at War is a very good game, but i prefer MW and MW2 over it, only for the fact that in WaW the enemy tends to spawn RIGHT BEHIND YOU :