Its never been "great" or groundbreaking. Ever. But some of the classics were pretty good like World at War. The thing i hate about it is that the community is absolute garbage
I never played the MW series besides at a friends house...i heard they were fun. The games on their own are fun if u own a few but kinda gets old if u buy them all. I have WaW, Ghosts, and BO3. They are decent games (ok i admit it maybe i shouldnt have bought ghosts) and i have had fun in them all.