I agree with 35g700, World at War played completely different than cod4. Not just the running under the maps or juggernaut+mp40 overpoweredness, the game was slower paced. The maps were much larger so everything was longer range I loved cod4 to death, have over 50 days of play-time total between the pc and 360 version. W@W, played in the beta and demo, thought it was glitchy but it was a beta/demo and final would be slightly better.
Wrong, I wanted to like that game. I love ww2, and I love cod4, but I didn't love W@W. Played till I was third prestige (mostly cause friend were playing it and it was change from h3 and cod4) but I couldn't get into it the same way as cod4. Just wasn't the same, and I ended up HATING it by the time I sold it. Couldn't stand to play it all, was just too broken and unbalanced.
Haven't played black ops online yet (always play sp first) but single player is junk. The infinite spawning enemies of cod4, the "we're trying way too hard" of mw2, and the lameness of W@W. Basically all the negatives of previous cod iterations. Only thing I give Treyarch props for is the fact that its almost original, although it has the most over-played and over-used spy story of anything. Course if you don't read many books you wouldn't notice it as much, and I doubt a lot of the Black ops players have even finished an entire book.
The game is getting around though, hear so many people at school talking about it and usually they never mention their gaming habits publicly. It seems everyone likes to go black black ops on friday nights now as much as they want to go get plastered.