It was a good story, imo, but there was a bit of explicit violence once they got to Troy. (And even before, ie, a sacrifice.) It wasn't too much for me because I tend to gloss over that stuff as much as I can (when I can't cover my eyes like in a theater), but my threshold might be higher than yours.

I checked the rating of movies like Troy and 300, which were rated R. I think this book would probably be the same.