Dune is kind of a slow burn. The animosity between House Atreides (good guys) and House Harkonen and how it was a plot by the Padishah Emperor was underplayed at the start, I felt (David Lynch underscored it, but it came off as a kind of info dump).
The fact that the Harkonens were unspeakably awful and the Emperor was a sleezebag could’ve been established from the off, and then the reader might have been more invested.
The fact that the Fremen (Arrakis natives) and the sand worms were going to be the big deal, the game-changer was obvious early on, that Paul Atreides was going to be a kind of Laurence of Arabia, so bringing that to fruition was basically this slog of a waiting game. David Lynch tried to “solve” this, ie, explain why it took so long to develop, by introducing this stupid idea of having to train up the Fremen on these bogus bene gesserit (I think)“weirding modules” which kind of added to the white savior leitmotif when of course the Fremen were already established as being total badasses and predestined (in a narrative sense) to be Paul’s secret army.
The motivations of all the characters were pretty mooshy and unsatisfying generally. It mostly came down to “I’m a member of the Bene Gesserit order, attached to House Atreides (et al) or I’m loyal to such-and-such house or to the emperor, or I’m a Fremen and I must conduct myself as such.”
Paul Atreides was driven by loyalty to his murdered father Leto, while loyalty to his mother Jessica (who repeatedly saved him) seemed a bit hit-and-miss. His love affair with Chani (played by Sean Young in the David Lynch film) is built up a lot in visions before he meets her (“Tell me of your home world, Usul,” but she seems sidelined after (and they don’t even have any kids…?). She’s no more developed than any other character.
The rituals and mysticism was delivered by a kind of just in time need to know morphine drip and kind of built on itself rather ineffectually, as evidenced by Jessica giving birth to Paul’s younger sister Ala who was an “abomination” (cuz she drank the worm derived “water of life” while pregnant ) which freaked out all the Bene Gesserit sisters in a deus ex machina kind of way. You could almost argue that a lot of the mysticism didn’t contribute to the story.
It was obvious almost from the beginning that Paul was going to be the Kwisatz Haderach, which was another slow burn that you were just waiting to resolve the whole time. This was true of many new spiritual or strategic thing—you immediately know which cubbyhole to stick it in, and little development was added after the introduction.
In the whole “we’re attached to House Atreides, so we’ll be loyal to the death (even beyond), even if HA is completely destroyed we’ll hang out in the desert “ unselfexamined character motivation and arc, we have Gurney Halleck and Duncan Idaho. Both are fighters for HA and also besties with Paul, for reasons which are never really explored.
House Atreides is destroyed (by the emperor and House Harkonen, again, which could’ve been better developed as a pretext), and Paul and Jessica barely escape into the desert Duncan is killed (later to be revived by the Ixians and return as a ghola—which may be in the second book Dune Messiah) and Gurney disappears only to return at the very end to play a (small) part in the final triumphant revenge sequence. Whence this loyalty and attachment? Duke Leto is a great guy, but this isn’t developed either.
Character motivations are a problem. Conflict is a problem. There are too many “sworn enemies” and “abominations” and “loyal vassals” and not enough backstory.
The spirituality and mysticism (the Bene Gesserit, the Spacers Guild, the Mentats, the planet Ix, the Butlerian Jihad behind it all, and so on) was interesting, but was largely sidelined or deus ex machina. Imagine The Bible, with Jesus, Abraham, and Moses having visions, yes, but instead of walking on water or turning it into wine or leading his people across the desert , he’s kicking ass with a knife made from the tooth of a sand worm riding vast numbers of worms with his newfound buddies to rain nuclear vengeance on his enemies…and all that after having to read through a similar quantity of pages to the Old Testament and the Gospels combined.
And what do the Fremen get out of it? They live in the deep desert anyway, and their dream is to transform their planet into a lush paradise, to which end they have been stockpiling water in vast underground cisterns for generations.
How does helping Paul Atreides kick the Harkonens off Arrakis further this end? Does he ever even promise to help them? Do they even need his help? It’s almost a Laurence of Arabia needing an army and a Great White Savior for a people who don’t seem to need saving.
Okay, maybe they needed the nukes to get rid of House Harkonen and capture the City of Arrakeen, but was that ever a priority, and mightn’t they have done it by themselves? The “oh, yeah, now we can do that” doesn’t seem to come up.
So perhaps Dune has the same appeal that many religions do—everybody else seems to be into it, it’s mysterious and often intricately beautiful, but ultimately long and boring and doesn’t make a lot of sense.