There are very few books that grab me the way Dune does. It's an amazing work of science fiction, and among the best books I've ever read, possibly the best.
I read Dune the first time at roughly 15 years of age, the age of Paul Atreides as the book begins. Whatever was going on in my life then, it let this book sink into me in a way few others have, and despite 30 years and innumerable re-readings, it continues to satisfy.
At one level, Dune is a science fiction story. It has a hero and a complex set of characters set against a backdrop that is foreign but understandable. At another level, Herbert went way beyond what anyone had done before. Written in 1965, Dune is an ecological novel, telling the story of an entire planet and the people that live upon it. I understand that Herbert did something like ten years of research before writing Dune, and it shows. This is a work well ahead of its time.
A quick synopsis: Paul Atreides is the son of Duke Leto Atreides. Duke Leto has been instructed by the Emperor to take possession of Arrakis, a desert planet and the only place where the spice, melange, is found. Melange has several properties, but most importantly it extends life, and it is a drug allowing altered mental states in some. For Space Guild navigators, it allows them to see far enough into the future to permit faster than light travel. For the Bene Gesserit, it permits and inward transformation so their members can access past memories.
Duke Leto, however, is opposed by Baron Harkonnen and others. Leto is killed leaving Paul and his mother to find shelter with the native inhabitants of Arrakis, the Fremen. There Paul comes into adulthood in a hostile environment and sets about taking back that which his father lost, and then some.
With Dune, Herbert hit a peak that I am not at all sure he ever reached again. Subsequent books in the series - Dune Messiah, Children of Dune, God Emperor of Dune, and others were OK, but don't measure up in my estimation. Dune is a singular achievement, and stands alone.
A brief story about the first time I read Dune: It turns out that my mother was reading it while I was in school. I came home and read in the afternoons and evenings when time allowed (often) and one night found me nearing the end of the book. Dune is large - my paperback is 537 pages - but I literally let out a cry of anguish when I learned the book ended some 50 pages shy of the cover. There were appendixes of various sorts after that point, but no more story. In the kitchen, though, I heard my mother's knowing chuckle. She'd finished the book a day or two before and knew what happened.