For me, documentaries need to achieve one of two objectives to be truly outstanding: they either need to transcend the genre and become a distinct and sublime work of art through the creative process of the auteur (e.g. Sans Soleil); or they need to provide a definitive account of their subject - as would a great historical text - with artistic profundity (e.g. Shoah). The Vietnam War falls into this second category.
This documentary is pretty far removed from any analysis about imperalism. Follow the money, and you will understand more than you will after watching this. But needless to say maybe, there are many interesting clips. I just saw Ken Burns praising John McCain on Twitter today, that should be a proof this should be taken with a grain of salt.