Sand and Silence
The 2021 film made a deliberate argument about how to adapt this material, and the argument can be stated in one line: withhold the explanation and let the world do the work. Almost everything in it is built on atmosphere rather than exposition. The dunes are enormous and slow, the sound design is oppressive, and characters often sit in a dim room saying little while the camera studies what the light is doing.
It works. More than works, it is the best-looking version of the desert yet made, and for a while the screen version finally feels like the planet the novels describe rather than a set. There is a scene near the end in which a young woman walks alone at night through the open sand and the film holds on her for so long that you understand something about the scale that no amount of dialogue had conveyed.
But atmosphere is not explanation, and the cost is real. A viewer who has not read the books comes out of the film unable to say who the houses are, what the substance is worth, or why the marriage matters politically. The court intrigue is compressed into glances, and the great institutional machinery that gives the first novel its shape simply is not on screen. Paul becomes a figure of destiny rather than a boy being shaped by people who need him.
The novel's genius is that it is a political book written in a voice that keeps reminding you it is a political book. Strip the politics out and you keep the atmosphere and lose the argument.
My own verdict is that the 2021 film is a superb adaptation of the mood and an incomplete adaptation of the subject, and that this is not a flaw in the making but a consequence of the scale. Eight hundred pages of institutions cannot be carried by silence, and silence is what this film does best. Which means it is an excellent door into the books for the reader who has the patience to open them afterwards, and a poor substitute for anyone hoping to learn the shape of the series from it.