To begin with I am a fan of this series of games and really like the way in which it has grown. However the honeymoon period with black ops is well and truly over. The single player campaign is good and not to short, but the real reason anyone buys these games is the online play.
The online play is good with less glitches and less problems with people leaving the map, however the lobby is unstable and drops party members very easily (hopefully a temporary issue). The kill streaks are a mixed bag of interesting and just copied form MW2 and WAW, there now isn't the game ending nuke which is a good thing. The whole buying your own guns, grenades, attachments and perks is good but at the same time you still have to wait for certain guns to be unlocked by online level progression. Now so far everything seems great, but then if you are a fan of the hardcore game mode (like I am) then here comes the greatest disappointment of all there are only 3 game modes in hardcore (Team death match, S&D and free for all) gone are the HQ pro, hardcore sabotage and others. Also to add insult to injury Ricochet is gone as well so team killing is back, but this has been addressed by kicking players who commit 3 team kills during a game session (which isn't helpful if you throw grenades that team mates run on to and die) I have seen numerous people kicked due to kill streaks killing 3 members of their team or due to unfortunate grenades. The game is 100% improvement on WAW, how could it not be, the maps are really well designed but it's only about 85% the game that MW2 is and not as enjoyable.