I liked the Dune movie, but to be honest I don't know why anyone is trying to turn any substantial novel--and Dune is certainly that--into anything less than a big-budget series, a la Game of Thrones. It's not like the old days when a tv show was, cinematically, bound to be worse than a movie. You can make equally high-quality work in both media, so the question really comes down to the shape and length of the story.