Excellent adaptation. Condenses information in a way that a newcomer will get the gist of things but addresses the complexities of Herbert's world enough to stay true to form.
I was astounded by the Sardaukar scene where they are preparing for battle. It made me shudder with awe. The music, inverted sacrificed bodies, and the malevolent voices were a combination like nothing I've seen before.
The absence of the Emperor and some of the other elements of the Imperium and space travel had me wishing for more. I hope at least some of that makes it into the director's cut. I understand that some people and critics are possessive of Herbert's work and enjoy playing the role of cognoscenti, but in all reality, this movie is amazing considering the restraints placed on a 2.5 hour film. I don't think anyone could have done better - except maybe Jodorowsky ;).
I am really looking forward to the second film.