This book was originally published in French, so I read the English translation.
The inside cover of the book states, "Complex Relativity proposes a representation of presently observed four physical interactions in a 'complex' time frame, where the four purely Real or Imaginary dimensions of Einstein's General Relativity become four complex dimensions in Riemannian space-time." According to Wikipedia, Jean Charon "was a French nuclear physicist, philosopher and writer.... He was the author of over 20 books on physics, scientific philosophy, and computer science. He conducted nuclear research at France's Commissariat à l'énergie atomique (Atomic Energy Authority)."
My guess is that Jean Charon probably had close to a genius level IQ, which is reflected in this book. It is full of complicated high level mathematical equations which I could not understand if my life depended on it. If you can understand what they mean you may very well enjoy the book. It was not written for the general population. You really need to have a commanding understand of higher mathematics to appreciate the theories that the author is presenting.
Fortunately, the author wrote another book, The Spirit, That Stranger Inside us, which I also reviewed. It is a much simpler presentation of his theories, without all the math. I recommend that book if you are interested in Jean Charon's theories.