I absolutely agree about Herbert not being a good storyteller or writer. I found it a difficult read simply because of the prose, and I really didn't like his use of an omniscient narrator. I don't really like omniscient narrators in general, but I found Dune's narrator especially difficult because of how freely it switches between characters. I often found that if my focus slipped even slightly, I'd realise a couple of minutes later I had no idea whose perspective the narrator was giving any more and have to backtrack paragraphs or even pages to work it out.
I think I perhaps appreciated the book more than you, but I didn't find it an enjoyable read. It certainly gave me a greater appreciation of the film, though, which I also very much enjoyed! And I'm glad I read it simply because it's such an influential book in a genre I love - it's interesting to see how so many things have build from its foundations.