Destructoid - Call of Duty: Black Ops II broke retail records a mere 24 hours after the public debut of the single-player campaign. An impressive feat, considering that multiplayer, the franchise's bread and butter, wasn't even shown off until just a week ago.
It's a good thing for fans that Treyarch isn't a studio who would just settle for minor refinements, then. They very well could have, but instead, the team has rebuilt the multiplayer system so much that you would be forgiven for thinking they're insane.
The Create-a-Class system as you've known it from past Call of Duty games -- and pretty much all first-person shooters these days -- is dead. Treyarch challenged the assumptions of what multiplayer in an FPS should be and has created something that makes the Call of Duty experience feel fresh again.