A frustrating experience
Call of Duty: World at War fails miserably to standout from other games in the genre. I was absolutely floored by some of the set pieces in the game and it may very well be the best war game ever presented. The game also features the most enjoyable flamethrower I've seen. However, these parts lose much of their value in the context of this game.
World at war is considerate enough to have every problem that this series has ever had. The AI of your teammates is terrible and they are there for almost nothing rather than the presence of having allied characters onscreen in a war game. Most of the time they are incapable of hitting enemies on their own, even when they are point blank in front of them. In fact, at times they will let enemies run right by them to hit you, exposing another problem of the series. The enemy is far too focused on your character, throwing any sense of "war" or "scope" out the window and you might as well be taking down the aliens as a one man army. Games with more meaningful squad based mechanics blow this series out of the water, as it hasn't decided to embrace being "arcade-like" or realistic, leaving it awkwardly hanging somewhere in the middle.
Another problem the series has had is the simplistic level design. The only way to progress typically is it to advance along the battlefield, pushing the enemies spawn back and you encouraging your allies to move up. As such, smoke grenades have been a key to success in the series giving you precious cover as you move up (considering you'll get none from your teammates). This tug of war shit is frustrating considering you're the only thing capable of landing a shot on the enemy.
The problems with the AI standout even more on Veteran difficultly, which you'll probably want to play on since the achievements (and I presume, trophies) require it. Now the AI will almost immediately gun you down once you've come into view, requiring you to very slowly strafe out from behind cover to be able to shoot them before they shoot you. With no proper cover mechanic, this simply isn't (and hasn't been for sometime) fun. Meanwhile, the amount of grenades the enemy will rain down on you would be hilarious if it wasn't busy making the game almost unplayable.
As for the multiplayer, its still good but it falls short of COD4 even by today's standards. The inclusion of online co-op is nice, specifically the zombie nazi scenario that is unlocked after you beat the game. The multiplayer suffers from some weapon balancing issues, as the submachine guns simply outclass everything else. Limited recoil and reasonable damage makes them as good as anything else for mid range targets while their dramatically better hip firing accuracy than anything else makes them far better for close range combat. Bolt action rifles and the shotgun suffer from lengthy wait time between shots. I did find the semi-auto rifles a bit fun to play with, but their limited clips mean you stand little chance against someone with a submachine gun typically. Simply put, the guns aren't as fun as modern guns which isn't really a huge surprise. The addition of dogs as the reward for kill streak of 7 is fun, but considering I had a dog strike kill 11 people in a minute, overpowered.
If you want to play this series' fantastic multiplayer, stick to COD4. If you want to experience WW2, watch Saving Private Ryan, Letters from Iwo Jima or Enemy at the Gates (all of which this series has been nice enough to blatantly rip off.... Ahem, draw from the same source material from).