I've been playing on the play list with the maps from the newest MW2 and I think that the maps are actually pretty decent. Yet I really didn't like MW2. So my dislike of it was purely down to the design decisions of IW. Specifically the loud footsteps that just slowed the game down.
On another note: I really don't like a lot of maps from the OG MW2. I think the majority of them are just far too big for 6v6. And they're definitely too big for FFA.