What makes Dune singular: the scope of its world-building (ecology, religion, politics, and prophecy all woven together), the density of its ideas, the messianic arc of its protagonist, and the sense that you are reading something genuinely important. These books share its ambition — whether in world-building depth, political complexity, or the sheer scale of their vision.
Yes — Frank Herbert wrote five sequels: Dune Messiah, Children of Dune, God Emperor of Dune, Heretics of Dune, and Chapterhouse: Dune. Brian Herbert and Kevin J. Anderson have also written numerous prequels and continuations set in the same universe.
Dune Messiah — it's shorter, darker, and functions as a stunning deconstruction of everything the first book built. Herbert deliberately subverts the messianic arc, and it becomes clear that the Dune series was never meant to be a straightforward hero's journey.
Its world-building methodology became the blueprint for modern epic sci-fi and fantasy. Herbert showed that a fictional world could be as deep and internally consistent as a real one — with working ecology, living religion, functional politics, and a history that predates the story by millennia. Almost every large-scale fantasy or sci-fi world owes it a significant debt.