I'll definitely need to rewatch Part 1 before I see Part 2. I'm intimately familiar with the original books and the 1984 and 2000 film versions, so it's less about needing a reminder and more about wanting to get back into the flow of this adaptation. However I'm pretty sure that most moviegoers will not remember anything that happened in the first film, so I wonder how many people will be motivated to see Part 2.
I also wonder how far the movies can possibly get in the story of Dune. I can't be the only one thinking about the long game here. Will Villeneuve get to cover Dune Messiah? Children of Dune? That's at least two more movies right there. Then the story gets weird with the fourth book, God Emperor of Dune, where Leto II turns into a giant worm. I think that part of the story would generally be considered "unfilmable" so it feels like we will never get farther than the Sci-Fi Channel got in 2003, which makes me despair a bit. But Children of Dune can at least be considered a somewhat satisfying stopping point, if they get that far. Technically Dune Messiah can work as a stopping point too, albeit it would probably be a downer for the audience.
Regarding Part 1, I think the production was obviously fantastic, but Villeneuve committed a big blunder: he tried to tell us, not show us, that Dune is an epic story. He does this with frequently ponderous direction and a soundtrack that literally shouts at you that this is An Important Story. Past Dune adaptations never had to do this; the story will naturally reveal its epic nature as it goes, through the powers of its characters and the scale of the world.
I also didn't feel much of a connection with the characters, as they are mostly uncharismatic. Chalamet himself is fine, but his character is written as a "relateable" insecure teen instead of a young man brimming with confidence who is the product of some of the best tutelage the universe has to offer, and who is living up to his teachers' expectations. Witness the building manic intensity of Kyle MacLachlan's Paul in 1984's "Dune" and compare that to the unsure sensitive boy in 2021's "Part 1" who says, "What if I'm not good enough?" I'm very curious how Villeneuve intends to turn this Paul into a desert warlord who longs to redden the sands with Harkonnen blood, not to mention a prophesied religious leader who leads thousands of death commandos. It doesn't seem like he can get there from here, does it?
I'm disappointed by how Jessica was handled, and Chani failed to make any impact in her brief screen time at the end of the movie. Sorry, but Zendaya has none of the presence of Sean Young or Barbara Kodetova. I get the impression she will just be a sort of bland girlfriend for Paul, instead of an alluring gateway into an exotic, violent and dangerous world. (Remember the part in Dune Messiah where it turns that out that Chani has been killing some of Paul's challengers who she deems to be unworthy of a fight with Paul? Male challengers? I don't think Villeneuve does.) One part I can give kudos to is the depiction of Duncan Idaho, because even though he seems ultimately unimportant as a character in the early story, those of us who've read the book know how important he becomes later. Past Dune film adaptations didn't give him much presence or screen time, but any investment made in Idaho early on will pay off later.