With a funn multiplayer and a lot of content, cod bo2 is a balanced experience without advantages and with no noob-friendly things like bo3 and bo4.
The campaign is great, awesome characters and Mendez is one of the best villains in the franchise. The replay factor does exists with the possibility of u choosing your equipment before the mission and different choices.
Somethings are bad, the lag does exists and affects the experience and sometimes the story feels kinda rushed.
Extra: the soundtrack is amazing
In the end, bo2 is a well balanced experience mainly in campaign and with well rewarded skills in multilayer mode.