I saw this Thursday evening. It's beautiful. Incredibly well-shot, acted, and directed.
There are, yes, some big deviations from the original story as laid out in the book.
Spoiler!
The changes with Chani will be unpopular with some, but it makes that character more real and fleshed out. Chani just is not a background character in this universe, and she serves as the cautious counterpoint to Paul's Messianic nature and standing with Stilgar and his like.
That's stuff that could be handled with internal monologues in the books, but not so much in film.
I thought the performances of Chalamet (particularly after Water of Life transformation), Ferguson, and Butler were particularly strong.
I'll watch it again. And look forward to Children of Dune.
I’m guessing we get Messiah as the final chapter no?