Frank Herbert's universe had seemingly endless plots, subplots, characters and themes. Dune has all the sex, violence and political machinations of Game of Thrones while also concentrating on much more weighty issues like technology, ecology, drug use, spirituality, the destiny of mankind, etc. The depth of Dune is too much for any movie to come close to capturing and that's the brick wall that David Lynch runs into. He can't possibly do the source material justice; not on a thematic level anyway. He can only capture the forms and some of the spectacle from the first book.
That said, I did enjoy it slightly more this second time, probably because I was focusing on its artistic merit and what David Lynch does well rather than mercilessly comparing it to the scope of the books. The first half of the film is steady, well presented and follows the book fairly well but somewhere around the middle of the movie the pace dramatically speeds up and they start cramming way too much story into too little screen time as events hurtle toward a hasty, contrived conclusion.
I wish that Lynch hadn't shoved so many of the characters thoughts into recorded voice overs. Apparently this was done because the studio demanded he cut his original 3 hour version of the film by 40 minutes. I get that anyone who hasn't read Dune would have a hard time comprehending what was going on without all that exposition, but I think the film would've benefited greatly by saying less. Let the mysterious remain mysterious and focus on those inspired visuals! If people want to unravel it all, they can go back and read the novel. What a torture, to have to read one of the most important works of science fiction ever!
For all its flaws, the film nails quite a few elements of "Dune." It's very well cast and most of the costumes / sets are spot on. Even the pronunciations of Herbert's fictional terminology are mostly correct and Paul's dream sequences are splendid to behold, evoking the symbolism and artistry you expect to flow from the prose of the book.
The film ends on a bit of an eye roll. Muad Dib and the Fremen win a crazy one-sided battle, he kills Feyd in the duel (Sting was surprisingly good in this role for someone who's not, primarily, an actor), Paul proclaims a new dawn of humanity and it suddenly rains for the first time on Dune. Really David? That rain wasn't in the book and you couldn't think of a better way to end it? How about after the proclamation we have a nice long zoom in on Paul transitioning into visions of the future from the subsequent five books? Muad Dib's fall, the trials of his children, the God Emperor and the rise of the Honored Matres! Paul is soaked in spice at this point so he's already getting glimpses of the future. Even just a brief montage eluding to those events with the dramatic score in the background would've made a great ending to your acid trip of a movie! But no, we get a sadly typical put-a-bow-on-it Hollywood ending and fade to credits.
Despite its shortcomings, I'm not overly disappointed. Adapting Dune is too great a task for anyone and it was fun to see Lynch try. Although much of the substance is missing, he succeeded in capturing the dramatic weight of Dune and painting a dazzling silver screen portrait of my favorite novel. It will be interesting to see if Denis Villeneuve can do better.