For the guys who took kids, anything that would upset a 9 year old in it?
I took my son (although he's 13), and I don't recall anything that would have upset his mom, which is the standard I hold to
As others mentioned, if the kid has played any recent First Person Shooter, there would not be anything that would upset them.
My son and I both liked the movie and thought it was a good departure from the normal, unrealistic action movie.
My son watches the history channel quite a bit, and likes the more authentic stuff.