I'm not sure what else I could add that hasn't already been said on 800+ audience reviews, except that I've been reading Dispatches by Michael Herr and some of the scenes in the movie seem to be taken from his accounts as a correspondent (I found out later the narration was written by Herr). The film seems realistic enough in parts, veterans of the war will say some of the battles are much like how they were (and that the USO show was spot on). Heart of Darkness combined with Dispatches seems about right. As it turns out, there's a retired Australian officer Barry Petersen who was just about a real-life Colonel Kurtz. Having had experience in Malaysia with the mountain tribes, the CIA took him on to lead the Montagnards against the Vietcong, similar to Kurtz. "By 1965, (Petersen) had fostered, according to his CIA bosses, a 'personality cult'." However when the CIA asked Petersen to step down, he did, avoiding the fate of Kurtz.
I've also watched Redux, the original is much better in my opinion!