I watched Platoon, not knowing what to expect, since I had not watched any of the Nam era films released before this, e.g. Apocalypse Now and Full Metal Jacket.  I had seen some of the comic book variety action films, like those done by Stallone and Segal, but no realistic films. 

Platoon was dark, heavy with anger, pain, killing, fighting, craziness and drugs.  In one sense it was unrealistic because routine life functions were left out, like eating, an occasional shower-shave, etc.  The result is that it hits your emotions hard because it does emphasize the dark side of Nam.