David Lynch is hands down my favorite artist and I can tell you that I have no reservations saying that Dune is a fucking godawful film. Just a total failure. There are some interesting concepts at play but, damn, just a colossal swing and a miss.
I've not read the book.
That's why I think anyone who hasn't read the book would probably really dislike the movie (as you demonstrated). Especially since the second half of the book is chopped up so much that it's more like a greatest hits version of the book than telling a complete narrative.
For example Paul and his Mother are out in the desert for a long time before they run into Stilgar and his Fremen tribe. In the movie it feels like they're only out there for a few hours at most.
Also the book goes into much, much greater detail on Paul and how he becomes the leader of the Fremen people. It's really unfortunate that the movie glosses over that, because it's a great part of the book.