Dune is a saga of 7 books, but there have been more books done by the author's children for exemple.

Set on the planet Arrakis, Dune is the story of the boy Paul Atreides, who would become the mysterious man known as Muad'dib. He would avenge the traitorous plot against his noble family - and would bring to fruition humankind's most ancient and unattainable dream.

It's been adaptated too in games and movies ( one movie should be release next year ).

The two first books are really great and for the fan there is the 5 books with the sequel of the story ( that span on several thousands of year ).

My judgement : For me Dune is a great serie, maybe my favourite.