F and I went to see it yesterday in the IMAX near the Heysel stadium. I think in retrospect I'd have gone for the 3-D experience rather than the IMAX; it is such a huge film that one rather gets lost in the perspective.
You have surely read the book, so the only important thing to say about the plot is that we get only halfway - although the film is being advertised as Dune, tout court, it's actually only the first half, up to the point where Paul and Jessica are adopted by the Fremen. So assuming that the opening night in the US in October is successful (and I think it will be), there'll be a part 2 next year, or in 2023.
What to say: it looks fantastic. Sets, effects, planets, big buildings, big bangs, ornithopters you can almost believe in, and of course the sandworms. (F wondered if the film-makers had drawn inspiration from SpongeBob's Alaskan bull worm; it's pretty clear that SpongeBob in this instance was inspired by Frank Herbert.) Here's the trailer which gives you some idea (though you really have to see it on the big screen).
So, other things to comment on. The casting is good. I want to particularly note Rebecca Ferguson, who despite her name is Swedish, as Lady Jessica, Paul's mother. She is less hard-edged than the character in the book, but I think deeper for it. Charlotte Rampling basically just gets one scene as the Reverend Mother, but steals it completely. Javier Bardem is Stilgar, leader of the indigenous Fremen, and is superb - the first scene where he brings the "gift of water" sets the tone. (I helped him with an event in the European Parliament in 2012 - see here at 0:37.) Jason Momoa is great as Duncan Idaho. Slightly less convinced by Josh Brolin as Gurney Halleck. The nobles - Oscar Isaac as the Duke, Stellan Skarsgård as the Baron - are fine. Sharon Duncan-Brewster, who I last saw as Daniel's friend and Edith's girlfriend Fran in Russsell T. Davies' Years and Years (which I don't seem to have written up), plays a genderflipped Liet Kynes. The two young leads, Timothée Chalamet as Paul and Zendaya as Chani, are good to look at and manage to carry off the freighting of youth combined with destiny very well. There is justifiable commentary that although the Fremen are ethnically diverse, none of them are actually played by actors whose ethnicity comes from the desert.
But the casting is secondary just to the staging and cinematography. All the key moments are there; some of them look as good as I had hoped, most of them look far better than I'd hoped. The music is just right too, though I was a little sorry that the Pink Floyd from one of the trailers didn't make it to the big screen:So, it will get one of my Hugo nominations for next year. I think I may still vote for Shang-Chi and the Legend of the Ten Rings ahead of it, though.