True, the maps are larger, but is it just me or do the SMGs fire like lasers? (Especially the vector with a grip). For that reason, I've been doing fine even on big maps with SMGs.
Other observations:
They got rid of Demolition and Search and Destroy, my two favorites, WTF?
Most maps don't have discernible routs, or the routs peak out at other ones, meaning a million lines of site to guard against, and death from any angle. This adds to the utility of SMGs. Gotta be quick.
Spawn system still fucked. They said they fixed this in MW3, which became obviously false when I and a teammate spawned in full view 3 feet in front of an enemy (he saw us pop into view). Have spawned near enemies here, but nothing that bad yet.