I refuse to call a movie horrible just because it wasn’t as good as the book. If that were the case, most of them would be horrible.
For something like Dune, I have to forget the book and watch the movie on its own. About the only movie where they’re equal is 2001, because the script and book were written together.
In my experience the only other book that was done almost true on film was "The Maltese Falcon". The book is in my top five and so is the movie.