W@W was a ripoff of COD4 set in a different war. For god sakes they stole the game engine and put new clothes on it
World at War used the same engine as Call of Duty 4, yes, but does that really make it the same game? Halo hasn't changed engines. Nor has Battlefield. I'd say that there were more improvements from Call of Duty 4 to World at War than there are from CoD4 to Modern Warfare 2. World at War was unique, with what realistic gun sounds and looks, gore and language, and the great campaign. As far as multiplayer goes, Treyarch had it nailed. Local search (which is worth more than any engine could ever be), gun diversity, much better spawns, weapons dominated at their specific range and didn't just outclass every other gun. Not to mention the rifle grenades were only unlocked after 150 kills with a semi-automatic rifle, and you only got two per life. Most kills in WaW were by actual gunfire, rather than grenades, RPG-7's, killstreaks, grenade launchers, etc. The maps in WaW were the best maps ever created for a first person shooter - it's undeniable.
Plus, WaW had Nazi Zombies, which was great fun.