I have not read the book yet, but from what I have read about it, I get the felling there are elements of truth and also elements that are off. De Vere mentions he used the "Derkesthai Process" in which information is channeled through archetype. I have always felt channeled information to be unreliable. I also have reservations regarding the caste system. I feel it is something that is not suited for modern times.
All the best