I think mw2 was better all the way around. Black ops feels like they cheaped out. The maps are knock offs of other call of duty designs weapon power is constantly changing the sniping is no where near realistic. Black ops has alot more problems then mw2 ever had.
Sniping in Black Ops isn't realistic as opposed to those realistic quick-scopes and heart-beat sensors, right? Let me tell you about something called bullet-drop, that's when gravity gradually pulls the bullet down, and the variables caused by the wind when actually sniping. Neither game is realistic and to imply one is moreso than the other is asenine.
The reason weapon power changes is because that's Treyarch responding to the community when they say something is over-powered (AK-74u), that's called balancing. Remember the UMP in MW2 that was never tweaked? Just sayin'.
And about the whole 'maps are knock-offs' thing, yeah, MW2 has maps ripped straight from CoD4. For emphasis I'll say it again, they're exact replicas. Familiarity really shouldn't bother you after that.
Valid arguments, please.
And to the original post, MW3 is the exact same. Linear levels, predictable Micheal Bay esque set pieces, and even the same engine as MW2 all thrown in there. Have fun with those destructible enviornments, though. Oh wait...