I liked the Dune movies that Sci-Fi made, but I never read the books, so I don't know how faithful it was. And I've only seen the original as a little kid.
As far as the Lord of the Rings, I've only read 2 Tolkein books, one was The Hobbit, and one was The Fellowship of The Ring. As far as I'm concerned the guy can't write for shit. Don't get me wrong, the story and characters are good, but the guy writes horribly. I don't have a boner for Peter Jackson or anything, but he made those movies the success that they were, he was working with shitty material.