Simply intense single player with a tried and true COD4 multiplayer creates a solid FPS experience.
The single player campaign seems to be more intense and involving than that of COD4, but the theme of technology creating an emotional barrier towards the gruesome ways of war is absent for obvious reasons. Instead, Call of Duty: World at War turns up the intensity in numerous and often bloody fights that may leave you cringing at some of the more violent moments. World at War sort of relishes you being in the most frightening of places in the war and when it keeps you in this state of dread, it's where the game truly shines.
The multiplayer is simply an once-over of the multiplayer from COD4, which is hardly a bad thing at all. I do wish they added a little more to the game when it comes to multiplayer.
In the end, World at War is simply for people who want a sort of "mod" of COD4's engine. If you prefer the theatrics of World War II, then World at War might be your cup of tea.