I agree that the pacing in Dune was uncommon, but for me it fit quite well with the story, as it doubles the feelings Paul must have felt within the audience. He and his family is exposed to bigger forces and can do nothing about it, while being exposed to dreams and visions of far off places, all with a hint of puberty which is disorienting in it's own right. So a lot of this emotional "unguidedness" is part of the material the director worked with.

Whether Paul or his family works as a projection surface for the viewers or not seems to be a bit of an individual topic. I personally didn't feel unable to empathize with the protagonists. If anything the untypical impending doom (like in a greek tragedy) that is so rare in hollywood cinema nowadays made me care in a different way. Yeah, Paul is the hero, but you can't shake the feeling it is not gonna end well. Instead it made me ponder more about the world and society that produces such fates and where one would find parallels in our time (opiates in Afghanistan maybe?)

I like it when the filmic world is the protagonist before anybody in it and these films are sadly quite rare, especially with a decent production.