The film is violent, but it's all justified by the plot, and in some scenes, Mel pulls his punches. Can't say anymore because I don't want to spoil it for anyone, but this is not just Rambo in the jungle.
I was also impressed by the writing. The action gets more and more suspenseful as the plot unfolds, and you think, this is it for the main characters...can't say more, it'll spoil you.