Having watched the too-long-awaited Part Two now at four theater showing in one week, and having seen the 1984 David Lynch version as it was released, and after, I feel qualified to offer an informed review.
Now, 40 years after the foment created by Lynch's release, the hubbub remains the same: novel versus cinema, and does the latter do justice to the former. My reply is a solid "yes" and for both films. Both succeeded in expanding Herbert's creation FAR beyond the "clergy" of faithful science fiction readers and into the wider audiences of cinema. Both did so with admirable success using the available technologies of their day.
The "debate" between sci-fi novel zealots and cinephiles is a false conflict. it is unreasonable to demand a science fiction saga be condensable to a few hours on film. The printed word has all the time in the world to spin its tale, to expound on histories, intricacies, subtleties, and topography. The cinema has a demand for economy. It's that simple.
Devotees may yearn for this or that to be present from the word to the screen, but those demands are akin to a diner going into the kitchen and directing the chef to change his creation.
The film adaptations of Dune must be given license to be their own entities, not faithful missionaries of the True Faith. Both succeed in dazzling array. I won't burden this review with a detailed comparison, but both succeed in breathing 3D life into the 2D novels.
Dune Part Two is the resolving chord to the unresolved first movie which revised the saga after four decades. Go and hear the seventh progress to tonic. Enjoy the peace it brings.