About Dune, there are two movies based on this book, the one from the 80's and a more recent one done by the SciFi Channel, which I believe is the better film. It doesn't have as much mysterious nonsense and seems easier to follow.
Well, I have a rather strange relationship to the whole Dune-buisness. I read the first book and absolutely loved it. I read the second and didn't even finish it... Allthough Herbert stayed true to the characters, the whole holy war buisness taking place just couldn't match the epicness of the struggle taking place on Arrakis in the fisrt one...
For the movies, well... I don't generally like it when everything has to be epic just to be interesting (a common flaw with action-movies nowadays), but when a story was truly epic, then let the movie be as epic as epic can be. And "Dune" was a book far more epic than e.g. Lord of the Rings.
So I like the lynch version a lot more. Lynch is a very visual director, and letting Toto do most of the soundtrack was ingenius. The look and sound of that movie just cry "EPIC!!" in every scene, the Harkonens are depicted in an utterly perverse way as the came out of the book, and the main score is just a blow away. Especially if you, like me, saw the movie rather late and emidiately realise that you have heard that theme allready multiple times in your live, covered from bands like Satyricon and Saviour Machine... I just felt right at home.
It s true, the movie takes a lot of liberties when it comes to story, and if you don't know the book, you barely realise what's going on. Also, in the end they had kind of a rush, but they needed to be detailed in the beginning, because otherwise you would understand even less of what's going on...
I saw the other version too, it is longer and therewith has more time to go into details, follows the story pretty close... they just lacked the budget for the real epicness.
The Lynch version may not be very close to the book in terms of story telling... however it just FEELS like the book. And that rain in the end may also raise several logical problems, but it's dramaturgicaly perfect. Made me shiver.
Anyways, I consider Dune fantasy rather than SF.