It's one of the few shoot em ups that when I get it, I will play the whole of the campaign before the multiplayer
Same, i think all COD games have a unique storyline. COD 4 especially!
For battles in urban environments, which is a majority of COD 4 maps, I use my M16 with red dot sight. I have only recently started playing it, I'm Lv.9!
On COD 5 I'm Lv.45, so I have a experience with all my levels weapons.