Call of Duty: World at War does what it set out to do. Unfortunately, it set out to be exactly like Call of Duty 4. While Call of Duty 4 was a great game, this does nothing to advance the genre.
Pros:
-The single player campaign does not "screw up". It maintains everything that made the Call of Duty 4 campaign great to play, while putting it in the setting of WWII. The addition of the Pacific campaign was a great touch.
-Flammable environments. The flamethrower is definitely a good addition in the game, because it fits the time period. It also has very realistic effects, which always improve the game.
-Realistic weaponry. This was a problem with Treyarch's last Call of Duty game, where the weapons attributes were not accurate to reality. Of course, this isn't as obvious to someone who hasn't fired most of the game's weapons.
Cons:
-Multiplayer again ruined by tanks. Why do they add tanks and make them so strong? Sure, it is realistic, but as soon as a player gets in a tank, that player wins the game. Not fun to play. There is a reason Call of Duty 4 didn't have tanks, even though tanks are still used occasionally in modern warfare. Seeing as how multiplayer is a big deal, this is a hefty toll.
-Single player campaign is WAY too hard. Veteran difficulty is entirely based on luck. Every enemy will throw grenades at the same time so that you can't run, and they also snipe you from places you don't even know about. Call of Duty 4 had a good difficulty going. Veteran had you die in a few places, but you could figure out some new strategy. There is no real strategy to hide behind the one "safe-ish" rock, and hope they don't throw grenades while you are shooting them. It's all luck. Bad.
All in all, I think this game deserves an 8.25 out of 10. Not too bad, but wait for the price to go down. If you really need to play a Call of Duty game in the meantime, get Call of Duty 4.