Eh, Dune series is sci-fi. In fact, it's regarded the same way as Lord of the Rings is regarded in the fantasy genre, from what I understand. Oh, it's not high-tech and all, but it's definitely not sword-and-sorcery. Far from it.
Anyway, it's a very complex set of books. Filled to the brim with philosophy and symbolism; it explores religions, fanaticism, and psychological speculations. Contains political intrigue, gray characters, and rather complicated plot. It might feel dry for some people, but I love the series to bits, even if the psychobabbles do meander quite a bit. Heretics of Dune is looking very good. The culture(s) in the Dune series are fascinating. Primarily, the Fremen desert customs are expanded/explored deeply; they've even got their own language. I'd rate it very high as far as books go. As far as the genre-father goes, IMO, it's waaaay better than LOTR.
Anne Rice hurts my brain. Her prose goes well beyond purple, and her characters just get more and more... screwed-up. It's not the explicit/morbid/unorthodox materials that bother me; it's just the way they go on and on and are simply gratuitous.