This copy is exceptionally clean. The dust jacket is bright and sharp. There are no chips or tears and no discoloration or foxing. The back of the jacket and spine are bright white. The front image is vivid. The book is also uncommonly clean with no distractions. Note that the paper used in this production of this edition is different than that used in either the Berkley trade paperback or the hardcover book club edition. It is not a bright white, but more cream color. Often the pages of this text have further yellowed. The pages of this copy remain supple and smooth. This is definitely the nicest copy of this book that I've seen. 

More details about this edition: This book is larger than the book club hardcover. The book club edition has the same height as the other book club issues from the time, whereas the height of this book is the same as the Putnam first editions of Heretics and Chapterhouse. The book was created as a companion book to the Dune series by Frank Herbert and appeared between the publication of God Emperor of Dune and Heretics of Dune. The cover art is widely accepted to be that of Vincent DiFate, though not attributed anywhere in the book. Approximately 3000 of these copies were printed, most intended for libraries (according to McNelly -- see a screenshot of his comments in the images).