We've all been here before, but it might be worth going again...
I picked up COD5 World At War shortly after release, and have played about 40-50 hours. Single player is graphically similar to COD4, which already beautiful is still not a problem. The game also handles in the way you have grown to expect from the call of duty series. All the controls are the same as before, which is good for fans of the franchise like me because it's easy just to jump in and play.
This time around you get to play as an American fighting in the Pacific and a Russian fighting Nazis. I personally enjoyed the Russian side of things more, but burning japs with flames can be cool too. There are some great in game cinematic sequences to back up the solid gameplay mechanics.
As a huge fan of Call Of Duty 4, the multiplayer was easy to pick up and play with good success. When it comes down to the multiplayer in recent call of duty games, the fact is it just takes a lot of time to 'get' it. Most people don't do well for the first month or so. A lot of it is about learning every square inch on the map which takes time.
The new maps seem varied and good for various game modes, but I am not happy about the addition of tanks to a few of the multiplayer maps. I don't use tanks, so its annoying when you get killed by one, in the same way it's annoying when you get killed by a damn RPG in COD4.
Is this game worth buying? Yes. Multiplayer dude. Seriously.