Hunters of Dune, by Brian Herbert and Kevin J. Anderson.
I read this book last year when it came out, but it had been years since I had read the original Dune series. Now, reading it immediately after Chapterhouse: Dune, I am impressed by how well the two books flow together. My library has ordered Sandworms of Dune and I am anxiously awaiting it. Although, I do agree wholeheartedly with one Amazon.com reviewer who wrote: "The biggest gap between father and son is subtlety. What Frank Herbert implied with a sentence, B. Herbert and Anderson drag out into a paragraph-long explanation."