Have you read the book? Just wondering. I've read it twice, though the first time was a very fragmented experience; the more recent reading felt like a first reading in many regards. Anyway.
I saw it in the theater, and think I came down more favorable because of it. It is quite a vivid portrayal of the desert in one of several ways the film and story bare resemblance to Lawrence of Arabia (a film I don't particularly like, but think, as many, that the cinematography is top notch).
In the book, one of the more challenging things for me to visualize was "the voice" used by the Bene Gesserit to control people. I am a bit conflicted on its portrayal in the film. I never envisioned it being such a direct/overt act in its use; it's almost violent in the film. I figured it was more in the realm of a Jedi Mind Trick, a little more subtle.
There are two other visual elements I was curious about: the shields and, of course, the worms. I think Villeneuve and his crew nailed both. I really like the idea of the thin, barely perceptible, but immensely strong shield, and the red and blue was a fun sci-fi touch. I felt that the combination of the worms and some of the voiceovers regarding the worms/makers from the opening cast them in a more religious/holy light that I appreciated. To take the point further, the solemnity of the Fremen and their relationship with their land and the worms helps maintain a sparse and serious tone into which I could invest myself, making the whole endeavor seem more worthwhile. The movie may be vastly humorless, but I think that, in a sense, differentiates it from Star Wars and Lord of the Rings (two oft-read comparisons), while not making it less worthy of one's time or inferior.
Where I disagree with you is on the character work. I thought it was shoddy. Thufir Hawat is not given enough due or development. Leto Atreides is inflexibly solemn and uninteresting (but also kind of that way in the book), Duncan Idaho and Gurney Halleck are even more straightforward archetypes than in the book, and both Liet-Kynes and Stilgar get too little meaningful screen time. When a good deal of these characters are killed off, I felt very little emotion compared to when they are killed off in the book. In that regard, I think Dune has some of the same problems as the Harry Potter series, as the book version of both feature rich character work that the films fail to develop.
I'd also agree on Chalamet. He has a lot of personality, and while I don't think he's bad here, I don't know how well we can expect him to do such a serious role, full-on. I think Villeneuve and company would have been better casting a lesser-known/unknown actor in that spot. I also don't think a talent like Oscar Isaac is necessary for the role of Leto. Take lesser-knowns with lesser expectation and baggage from a movie star's career and use them to form the acting foundation. In this light, the worst piece of casting was Jason Momoa as Duncan Idaho. I don't need to see Chalamet and Aquaman going back and forth in that stilted sort of way. It was weird.
Overall, this thing is like a B-/C+ for me. I hear what you and a lot of people are saying about the ending, but as someone who really likes the book, I think it's near-perfect. The stage is set for an amazing second half. I look forward to seeing what Zendaya will actually bring to the Chani role, as I think she is one of the more interesting characters in the book that breaks the the mold of the worshipper and the worshipped that's so important to the narrative.