This movie could have been very salvageable if they had cut all non-essential dialogue. For example, when they get to the FOB. The crying and pep-talking doesn't work because I don't care about the paper-thin characters. They should have focused purely on making an action movie.
By the way, did anyone else notice that these guys didn't seem to act like, well, "soldiers" or "marines"? When they're first attacked and dealt a crippling blow, they were bunched up, slowly moving along the middle of the street. I'm not a military man, and hopefully I'll never be, but that just seems like something you'd just know not to do. Anyway, I think they should make a sequel. Cut out all talking. I think I speak for most people here when I say that I zoned when they got the FOB-thingy and he starts talking to the kid. Cut out stuff like that, and they'd have a much better framework for the sequel.