Who was the editor for the Frank Herbert novel, Dune? I've heard that the following books in the series were not edited by the same person and suffered for it and that a lot of credit to the novel's success should be due to the editor as Herbert's manuscripts where quite a mess.
It is true that Herbert worked with another editor/publisher for the sequels to Dune, but I would not say that affected the result much. The reality is Frank Herbert had a very strong idea of what he wanted and tended to go it his way despite what others said.
For the first Dune book Herbert worked first with John W Campbell publishing Dune stories in his magazine Analog. To publish the book Herbert worked with Chilton Books, specifically Sterling Lanier.
Lanier was released from Chilton and Chilton decided not to continue to publish Dune, so Herbert went elsewhere with the sequels. While writing the sequels John Campbell expressed unhappiness with the direction of the character Paul. Campbell eventually refused to publish the serials in Analog and Herbert worked instead with Galaxy magazine.
The thing is, Campbell complained, along with others about many other aspects of Dune. Everyone tried to get Herbert to remove the opening 100+ pages and start the story on Arrakis. Herbert stuck to his guns and wrote the book the way he wanted.
Ultimately I think the second two Dune books are not what fans wanted, but are the story that Herbert set out to write. One of an antihero instead of a hero.
(All of the information I shared here I got from the book "The Road to Dune".)
Edit: I added a link to the Google Books result for "The Road to Dune" that is the page with letters from Campbell explaining his concerns.