As for gender-swapping Kynes, I just couldn’t get behind it. I didn’t like it when they announced it and I don’t like it in the movie. Period.
Of course I’m not saying you have to like it, but why not? I’m curious why it makes so much difference to some. Maybe if it was Paul I wouldn’t like it either, but Kynes isn’t a huge character in the book or the film anyway.
Like I said, I just couldn’t get behind it.
Two changes I did like were Paul’s visions of possible future where Jamis becomes his mentor in the Fremen ways and friend, it greatly improved the scene where he sheds tears for a man he barely knew.
The other change I liked was making the crysknives longer. In the book crysknives are described as being 20 cm in blade length, but the movie added at least another 10 cm, which I approve of because 20 cm isn’t cinematically impressive.