I played and enjoyed the Black Ops campaign. Lots of explosions, shooting etc...For me it was sever hours of fun, for my neighbors it was like the 3rd World War had started (250Watts of explosions and gunfire, I LOVED IT). To be honest, the single player campaign is the only thing I played in Black Ops, I wasn't interested in multiplayer.
I did play every CoD (single player campaign) that got released on PC, but to be honest, Black Ops was the only one that stood out and kept me playing it...dunno why, maybe coz of the explosions that took place every freakin' 3 seconds.
PS: The only multiplayer I tried and liked in the CoD franchise was in World At War, the co-op story campaign and nazi zombies with 3 of my friends...Lots of laughs and good times.