In a discussion thread on reddit, one post claimed that Frank Herbert liked David Lynch's adaptation of his novel (until then I was under the impression Herbert never lived to see it, but I digress)- does anyone know if there is any truth to this supposition?
This does seem to be the case. Quoting from a 1984 People magazine article (web archive copy):
It's rare to find an author who feels that a director hasn't massacred his work, but after seeing a rough cut of Dune, Herbert is pleased. "They've got it. It begins as Dune does. And I hear my dialogue all the way through. There are some interpretations and liberties, but you're gonna come out knowing you've seen Dune." His reaction to the rock singer Sting, who plays the villainous Feyd-Raucha, "Ah, he can act!" As for those infamous sandworms, created by John (Star Wars) Dykstra and Carlo (E.T.) Rambaldi, Herbert was impressed: "They're realistic and scary. These are no Japanese monsters rising out from the deep to eat Kyoto."
Herbert addresses this at some length in the introduction to his 1985 short story collection Eye. His feelings were mixed, but overall positive, I'd say.
The hype machine grinded into action, telling people to expect the complete Dune. My efforts were enlisted. I joined in wholeheartedly because I enjoyed the film even as cut and I told it as I saw it: What reached the screen is a visual feast that begins as Dune begins and you hear my dialogue all through it.
Was it a success or a failure as a movie? I'm the wrong person to ask. Like me, Dune movie audiences, fans and newcomers, wanted more. They would have returned many times to see that "more." What they saw was true to my book, even though most of it stayed on the cutting room floor. Dune fans could supply the missing scenes in imagination but they still longed for those scenes.