I have read them all. I think the second book is better than the first, but the third is just downright horrible. And no, it is not that I specifically prefer science fiction. I read historical novels (Simon Scarrow is the author to read here), fantasy (Tolkien), science fiction (Frank Herbert) and horror (H.P. Lovecraft).
As for Dune... It is a fairly complex story, with intrigues and complications in every chapter. But if you want the short version, the first novel is about the Atreides family, nobles, and in particular the son, Paul Atreides. In the Dune universe, the most valuable resource is what they call "Spice", a kind of drug that gives you certain abilities. It can only be harvested on the planet Arakis, known widely as Dune. Coincidentally, the family has just bought that planet, leaving them with potential for ascending to a whole new level of power. However, another noble family, the Harkonnen house, has other plans.
"... for doubt and secrecy are the lure of lures, and no new horror can be more terrible than the daily torture of the commonplace."
- H.P. Lovecraft
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