Save your money. BO2 is just as bad as MW3, which was worse than BO 1, which was worse than MW2. Since MW2, its been downhill. This time the multiplayer rewards camping even more with killstreaks like the toy car and the hunter drone which are sure thing kills and completely ridiculous.
Its also, like hoof said, completely straight ahead gameplay. There's no trying to play tactically, because every map runs you right into the other team with really no two or three ways to get to a certain point on the map.
Halo 4 isn't bad.. but its not any better than Halo 3 or Reach. If you are choosing i'd say go Halo 4.. but i may take both back because neither are better games than their predecessors.