As a fan of both the book and the movie, I think there are different groups of people who didn't like it:

• The general audience that are used to instant gratification and explosions. These people will obviously find the world building and slow burn pacing boring.

• The more open-minded non-book reader audience who can appreciate a movie like Dune but just simply found it hard to understand all the new lore and world building crammed into a 2.5 hour movie.

• A similar group as the previous one, but who understood the plot, and found it lacking or bad, or just didn't like the execution.

• Dune fans who didn't like it. We have to accept that while the film is amazing, it does have its flaws. I guess some fans found the flaws outweigh the good parts.

watched Jorodowski’s Dune

I'm guessing you mean the documentary about it. Since it doesn't exist.

I've not heard many bad things, everyone I know who watched it really liked it.