If you ask me, the story mode seemed longer than MW1. In terms of the acts, they are pretty much at the right lengths, but the gameplay itself was great, I actually enjoyed this story mode more than MW1, had fun. Spec Ops mode is literally fun, it's challenging, even on Regular (I was getting into grips with the game mode first, didn't know what do it exactly), realizing alot of it was mainly based around stealth, reaching for intel, racing etc. Pretty much fun and enjoyable.
Mulitplayer is great, I love the fact they've added callsigns, People know you either as the F.N.G or any others (I'm still a F.N.G although I'm now at level 7).
Multiplayer is great, Spec Ops mode is great, Story mode is great. IW I think did themselves good, and if you finish the game off
(SPOILER ALERT)
So yeah, I love this game, Multiplayer is my next aim to get use to, was not that use to MW1 multiplayer since I got it around the time when the UFO hack came in.