I disagree, I loved Dune. Messiah was a little hard to follow, but Dune was ace. It felt like part one sanded off all the interesting bits and gave us a really generic brutalist aesthetic scifi.
Yeah, I have to concur with that take. When I read Dune, I just didn't find it that interesting.
It rarely felt like the characters had agency--a lot of plot tokens were collected and redeemed to move the story forward (whoops, story needs to move--time for a new, previously unmentioned superpower). And quite often the characters were just cartoonishly dumb or smart or good or evil.
As you said, it's certainly not for everyone. I suspect it's more a "product of its time".
I really wanted to like it, and the visuals were fantastic. But, I had no emotional reaction to the characters and feel like the plot was just flowing along without a reason for me to care. I gave it 30 minutes.
It suffers partially from contrived exposition. It seems whenever a Dune film is made, the filmmakers tend to try to include as much of the lore as tolerably possible. They could've just started off the first film with Paul entering a room to encounter Gaius Helen Mohiam and the audience being introduced to the box.