Lynch hated Dune. Lynch's name is removed from the credits of the original cut (replaced with Alan Smithee) because it's so embarrassing. It's still a Lynch movie, so it's interesting to watch. I would not call it underrated.

The tempo of the movie is completely off, and no cut has been able to fix that. The characters and scenes just run trough the story.

Lynch wanted Salvador Dali to design the set. Instead he had to reuses the set from the Conan the Destroyer (Richard Fleischer, 1984).

He didn't even get the music he wanted and that's big part of his movies.