Heretics of Dune drew me into the story just as all of the previous four novels have done. However, the lack of an Atreides main character hurts the book. Although Duncan Idaho is a substitute, he doesn't get as much page time as Paul or Leto II. I actually liked God Emperor of Dune more than Heretics (unlike most of the reviewers here it seems), as I really didn't mind the long, philosophical musings of Leto II. I thought Sheeana would take the main spotlight and I liked her spirit. Yet, she went into the background after the first half of the book and is going to be absorbed as a Bene Gesserit pawn.
I liked the action, which was missing in the last book. Teg's scenes, especially the escape and his new-found prescient powers, were the best in the book. Heretics is heavy on the Bene Gesserit plotting, almost too much, and it takes away from Duncan and Sheeana. The involvement with the Bene Tleilax was a surprise, but I am interested in discovering more. It is intriguing that the Face Dancers have become so adept at mimicry that they are forgetting even their origins. What does that mean for the society, if these creatures can seamlessly take over someone's life?
The original world that we set out with in the Dune series is now far into the future. The Bene Gesserit finally have a rival, the Honored Matres, who have the ability to fully control men, after having sex with them. Herbert took a strange angle with Heretics and I am not sure why it had to be sexual subversion. I am assuming it is the setup in the next book for some sort of parallel with human evolution of emotions and relationships. The Bene Gesserit control all of their feelings and for most of them, do not experience love. However, the notion that Duncan Idaho has been breed to be the ultimate sex enslaver, to outdo the Honored Matres, is kind of far out there. I am willing to not completely dismiss Herbet because he always seems to have a reason for everything. Maybe he was tired of writing about mental abilities and wanted to move towards physical?
I wonder if Odrade can change the Bene Gesserit. I am also wondering how Leto II's plan will be uncovered, and if anyone will ever know if the universe if working out to what he had intended. Now it is really only speculation. I was disappointed that Heretics was a build-up to the next book and didn't have a lot of plot progression, so that took it down a star.