I have not read the book. Is it worth reading? If so, someone please explain how great an experience it is reading this book!
It is *very* similar to the film. There are no changes to the story, there is a minor plot difference where there are no weirding modules, and the Voice is simply taught, which makes sense from a perspective of a milieu where guilds closely guard their secrets. There is some additional background to the Bene Gesserit which is implied in the film so you really are not missing much. The visuals in the Lynch film perfectly capture the background of the book's world.
Just to be clear - Dune (1984) is one of the greatest films ever made, and you either love it or you don't get it. I say that knowing full well that Kyle MacLachlan is horrible in it and that Jurgen Prochnow will probably go down in history as the most wooden actor ever. Despite ALL of the faults that Dune has, it still remains one of the most visionary science fiction films to have ever been made, and, it fully captures the story in the book, brings it to life, and adds to it.
I love the weirding modules. It helps explain how a bunch of random cavemen can use the Voice despite not being genetically suited for it.
I love the rain on Arrakis.
This is the most anal of all the subjects when it comes to Dune (1984) because there is no rain in the book. I .. will explain.
The spice is a quasi-magical substance that fantastically mutates people into creatures with outwordly powers. The Navigators are simple humans, but due to their excessive consumption of spice, they become horrible floating worm-things.
In the book's milieu, the elite take a small dose of spice and it prolongs their life. Specialist spice-users take much larger doses and, in conjunction with mind training and selective genetic breeding, they obtain magical powers. The Bene Gesserit have the Voice and precognition, plus a limited form of ESP. The Navigators have teh ability to fold space.
Dune strongly states that men and women are substantially different, no man can be a Gesserit and no woman can be a Navigator.
Paul is a special human, because of the genetic breeding program of the Gesserit. In the world of Dune, the guilds *are* the empire. The empire has survived the Butlerian jihad only because of the Guilds, so the Gesserits are deeply involved into *everything* that happens in the empire, not just every marriage and every child conceived, but through spice-powers, the genetic makeup of every child.
Paul is a glitch. Paul was meant to be a girl, in a scheme meant to produce the Kwisatz Haderach, the ubermensch. Instead Paul is born, and then takes the water of life, allowing this one human to have ALL the powers of spice use. Specifically, he can teleport, is prescient, has ESP, can control worms, lives forever, and, most important, HE CAN FOLD SPACE.
In the film the awakening of the sleeper (Paul "waking up", going from being a useless little shit to the ubermensch) is punctuated by his recurring dream of the crashing waves of water in his home planet of Caladan. During the ending rain sequence, Paul simply folds space and transports the water FROM CALADAN TO ARRAKIS.
That's it. That is the rain sequence. It absolutely fits within the narrative of both film and book.
.. honestly if you read the later Dune books you'll see that Herbert is a hack and i have zero issues with a script writer coming along and making improvements in a story which is what happens in 100% of good films. People who fucking idealize Herbert are just idiots.