I can handle a slow burn and have watched plenty of slow movies and TV shows and have read plenty of ponderous book series (LotR, Wheel of Time, ASoIaF, etc), but there is something about Dune that clearly shows it was from a different era of Sci-Fi. The themes felt much more simplistic than more modern stories, tropes that it had a hand in creating loom large, and there are elements of the story that, while clearly new to readers in the 60's, have become old hat now.
Unfortunately that becomes the challenge adapting something from close to 60 years ago with an ocean content since then. Do you update it and take some liberties or present it mostly as is knowing that it may feel dated. If the latter, then to me it comes down to performances of the actors, which were fine, but hardly memorable.