kyrios Perhaps one day I'll read the books.
You won't be disappointed. When it comes to SciFi, Herbert was a god!
The figure that's usually quoted for a movie based on a book, is that it requires one minute of motion picture to express one page in the book. I'm not sure if I believe that figure, because in my experience it seems more like 2 or 3 pages per minute. Obviously, it depends on the movie.
And just as obviously, a huge epic can't be done with a single movie, without leaving something out. Sometimes a lot needs to be left out. The moral of this story is, "If you enjoyed the movie, you'll probably love the book(s)."
In my own experience, I prefer the book(s) for content, and the movies for presentation values.
