For me, it's just another COD. I did buy MW2 and Black Ops nearly after their release. Both were fun, I enjoyed MW2 much more, though. For Black Ops I lost the magic in one or two weeks. I got simple bored of it.
CODs are almost all the same, Run-And-Gun. They aren't really good for competitive gameplay (Except MW) and in the end it will only last as long as you are addicted to it. You pretty much can't go back simply because the playerbase vanishes to new COD. So Black Ops 2 is just another COD game with nothing extremely new.
In my opinion, they should make whole new series with more of a competitive style. People will always stick to it as long as they can play competitively against other players and customize the game. Great example is Valve. All of their games are customize-able, which makes them so successful.