I remember about 10 years ago going through a Banes and Nobles in the history section looking for a new book to read and came across "We Were Soldiers Once and Young" and went ahead and bought it. Fantastic book that reminded me of E.B. Sledge's With the Old Breed (highly recommend this book and it is one of the books Spielberg is basing his new "Pacific" on).
So, when I saw the actual movie in the theater I was honestly pretty impressed with the fact that they were able to match the actors to the characters well and showed what these guys "really" did. It was just a shame that the movie only focuses on the FIRST part of the book and completely leaves the other half of the battle out.
So for me, WE WERE SOLDIERS has got to be the best Vietnam movie. Yes, Platoon, FMJ, Apoc Now are great and I really like them (as well as Green Berets) but all of them are fiction that is an interpretation of what actually happened. Yes, some of them get certain aspects of the military culture at the time but again, they are works of fiction.
What makes We Were Soldiers stand out IMO is the fact that these were real men. Real volunteers who knew they had a job, were honorable in attempting to accomplish their job and the acts of bravery that were exhibited by the men in the fighting were not idealizations of acts of bravery that a screen writer made up, but real acts of heroism and sacrifice. On top of that, while showing the need to accomplish the mission, the movie does a fantastic job of getting you to "connect" with the characters who have to accomplish the task. I felt sad for Lt. Geoghegan when he dies while trying to rescue his soldier (even though it was Hollywoodized for the movie) and the sacrifice his platoon made to hold the perimeter (all but 3 of his men died in the attack).
While Charlie Sheen and Berenger's characters in Platoon are based on certain types of soldiers, the hard nose Cmd Sgt. Mjr Plumbly that Sam Elliot portrays was a REAL person who really was like that. You watch this movie and the men in it and you see the basis for so many fictional "war" movie characters in them.
on a side note, another really great war movie that I highly recommend deals with a very little documented war, ie: The Korean War. IT isn't told from a US perspective but from a Korean perspective and is subtitled. It is viewed as the "Saving Private Ryan" of the Korean War. I am partial to it as I had famliy that lived in Seol that lost their lives during the war but still, it is a fantastic piece of work. It's called Tae Guk Gi.