I've loved the entire game so far. The only thing that I hate about online play that is going to probably be a game ruiner for me is the spawn system. People were complaining how bad MW2 Spawns were, but Black Ops is by far 10 times worse! 90% of a match the game spawns your team and the enemy team in the same exact spots on the map.
While we're all talking about New COD vs Old COD, I too miss the old COD (The first up until COD3). Those games were all about major battles that took place in WWII, and you played the role of an every day solider that experienced the battle first hand. It was like you were playing a game and having a history lesson at the same time! COD4 and onwards it's all made up storylines and battles that never happened (except COD:WAW). This in itself is pretty fun, but anyone who has played the COD series from game 1 will tell you they miss the older games more. I'm really hoping after Infinity Ward finishes their Modern Warfare (I actually really want to see what happens to Soap, Price, and Nikolai now), they set the pace back to the old style and have you fight histroical battles as an every day soldier. It doesn't have to be WWII again since there are many wars to choose from, but if they somehow do decide to go back to the old style then Treyarch will follow them back too (seeing how almost everything Treyarch does is do what Infinity Ward does and fine tunes the bugs out of it).