This is definitely one of the most interesting books about Vietnam. Olivier Todd, a left-wing journalist who confesses to being 'led up the garden path' after he discovered the real nature of the Vietcong in Hanoi, Saigon and the jungle. This is a very detailed look at the final four months of the Vietnam War right up to the fall of Saigon on 30 April 1975. Being an ex-left wing journalist, Todd also covers the 'Day after'. The Vietcong indeed knew how to wage war. But waging peace remained an elusive goal. Moreover, the victor in the following years also follows this up with the usual show trials, which appear to have become the hallmark of communist regimes.
I suspect that a lot of the information in this book has not been put in writing before. The real story about Vietnam has been 'revealed' in lots of books. But none of these revelations are complete. If you are interested in the Vietnamese War then this is a must-read.