The movie could have certainly done with a video game-esque five minute opening monologue explaining everything. I had to brief family members on the overall setting and basic plot because the movie assumes a lot of knowledge, I felt (particularly around who the Bene Gesserit are).

FWIW, I have never read the book, but had seen the Lynch movie and was obsessed with the video game which doesn't really cover a lot of the plot either, but I think does a good job of setting.