I read the book in the 70's but I'm not an aficionado or a purist who'll be offended by the simplification of the politics, intrigue and the missing characters. I understand the needs of cinema are different so I'll not criticize the film in that respect.
My thoughts on what remains:
Dull enough to make you doze off but so loud sleep is impossible.
Flat, 2d, undeveloped characters are becoming a hallmark of this director. Some of the players die but who cares. This film does not engage emotionally and where it tries (rarely), it seems clunky and inept.
After Blade Runner I thought I'd give Villeneuve the benefit of the doubt, maybe it was the atmosphere on set or perhaps the actors own interpretation that had given the film a dull uninteresting feel. After watching Dune I have to conclude that it's Villeneuve himself that makes a trip to the cinema a totally unremarkable and eminently forgettable experience.