I'll say this about COdBlops2.
Multiplayer is pretty much the only reason I buy the COD games. They don't change much from year to year, but they still do it better than anyone else. 15 Multiplayer maps at launch, and more game modes than any other FPS. I picked up Halo4 also, but CODBlops has about twice the content for multiplayer. That being said, the game is 95% the same as any other Cod, with new maps. Still, I felt like this is the most refined and balanced version yet, and the changes while small were positive ones.
For example, Killstreaks are now ScoreStreaks, so doing things like Capping/Defending Objectives, Assists, and pretty much doing anything of value helps ready your Streak rewards instead of some douche camping in the corner on an objective game to get his 25 streak to drop a Nuke. Also, I really like that the Air Warfare has been toned down a bit compared to previous CoD Games. MW2 I hated cause you would hop into matches where it was just nonstop Airstrikes, Choppers, and Predator Missiles. You couldn't take two steps sometimes without being blown up by random shit.
I didn't ever pick up MW3, so a few things are new to me in Blops2 that may not be totally new to everyone. They added the Hardpoint mode which is basically team King of the Hill, and it works well. I am a big fan of the Kill Confirmed game mode, which requires players to run out and pick up the dropped dog tags from your kills in order for them to count. This mode really makes people to work together more than standard TeamDeathmatch, since people are moving around more to pick up tags, and trying to reach a tag can lead to being ambushed. It is really a great adaptation of your Standard Team Deathmatch.
The New Create A Class setup is actually pretty damn amazing. Now, you basically have a max of 10 total weapons/attachments/equipment/perks/etc. that you can have equipped at any one time. But the big change is the new Wildcards, which open up new possibilities. Wildcards use an equipment slot, but allow you to do things like using 2 Perk 1's, or extra equipment, or extra attachments on your weapon. They really add a lot more options. You can go without a secondary weapon or grenades in order to make room for more perks or attachments.
As far as the Campaign and Zombies go, I have never really enjoyed either of those, so reviewing them would be pointless. But the Multiplayer is more of what you expect from CoD, lost of content, same old gameplay, with some solid general improvements.