Children of Dune

Amazing. Arguably the best book in the series so far. The themes of politics and religion are stronger than ever, the political intrigue and mind games are fantastic, the scope even bigger. And the protagonist is just fascinating. I have never seen a story deal with future sight and visions in a smarter, more compelling way.
Don't listen to anyone saying Dune gets worse after the first book. You cannot fully understand Dune without its sequels and they're fantastic books in their own right.