i have it, its pretty much the same gameplay, only this time your only in control of one squad instead of 2 like in the first one....there are some missions where you fight alone. Theres tons of weapons and vehicles to unlock. They added a thirdperson view. Thats basically it.
i cant play over xbox live until i get a broadband connection, and none of my friends would want to play it with me. So i have no clue what the mp is like =P