Fabled science fiction with deep description world building.
The book takes patience to read, not because it isn’t interesting, but because it is vividly descriptive. And if you’re imaginative enough, you’ll love the manner in which Herbert portrays a tapestry of intricately crafted storylines. Quotations from Princess Irulan at the beginning of each chapter set the tone, while religion is woven into the very fabric of the narrative. Each book in the novel series is as vast as any George RR Martin or Dan Simmons story universe.
Its actually difficult to briefly describe Dune. Essentially, there’s a Guild that monopolistically controls the trade of Mélange which is extracted from Spice which is only available on the desert planet of Arrakis or Dune. Mélange is a drug powerful enough that it allows users to harness space-time to travel across the universe, without messing about with plain old FTL ships or equipment. There a good versus evil war being waged between the noble Atreides who’ve been betrayed by the vile house of Harkkonen houses, unambiguously supported by the emperor (who’s pretty much a pawn of the Guild).
Character (and society) development is in-depth. The Mentats are trans-humans who have brains with supercomputing capability and are assigned to aid the nobility (various Dukes or even The Emperor). The universally feared Bene Gesserit are a religious sect who have fine-tuned language and perception to the point where they're able to persuade and convince other parties with seemingly supernatural ability.
There a wonderful writeup by The Gurdian on Frank Herbert. He had started off as a freelance writer and was once researching a magazine story about a USDA programme to stabilize shifting desert sands by introducing European beach grass. His research led to learning about deserts, desert cultures and even global transformation. Dune took nearly fifty ears to become established as a science fiction masterpiece.
Dune and the following series are science fiction hall-of-fame novels. While a difficult read for some, they are benchmark setting for authors in the genre.