This movie's reputation for being mediocre is, I'm sad to say, pretty deserved. While the costume and set design is excellent, the story was drawn out and weighed down by excessive amounts flat exposition. Good story telling is often built on building the story through action, "showing, not telling." And this movie has an awful lot of scenes where people literally recite the plot to the camera. This is partially because its a story built heavily on political and religious intrigue. Tales of societal stratagem often don't translate well in film.
The special effects are also kind of silly. Lynch is, as usual, obsessed with fetal imagery, and one of the main villains of the film has a distracting vagina for a mouth. The silliest effect of all though are the "shields" that the Family Atredies uses for protection (:53 in the trailer). LOL!
Not to say it isn't a visually interesting film, but you can really tell it was made in 1984.
I also really hate the depiction of the Harkonnens and the Baron in particular. Stupid, Gross, annoying! But it is fun to see Sting play the bad guy.
And speaking of weird celebrity appearances, this movie is like a who's who of nerd actors.
Brad Dourif played Wormtongue in Lord of the Rings. As Piter de Vries, he plays the almost identical character; a corrupt and nasty political adviser with close ties to major figureheads.
And Dean Stockwell, AKA Al from Quantum Leap as the traitorous Dr. Yuweh. It was neat to see him in something else.
I've actually been dying to see him in 1970's "The Dunwich Horror". He plays the lead in this movie based on Lovecraft's short story about demon worshiping monsters. It looks hilarious and he's so young!
So anyways, "Dune" is really long and kind of boring at times. Also very very weird. I wouldn't recommend it if you haven't read the books. The film is very true to the novel, but it's almost like because it's so word-for-word, it's not very good. I dunno. David Lynch's style and Frank Herbert's mythos is a weird combination.