Herbert's original material didn't really offer much for establishing the Harkonnen as horribly evil. Lynch inserted that with the gonzo-gore stuff about heart valves and whatnot, but since it's not in the book, it's sort of understandable it's not in Villeneuve's film, either. We simply learn the Harkonnen are not men of their word, with the Baron blatantly lying and betraying left and right.
Another thing Herbert never really provided was a satisfactory way of how the men of future would fight whole wars with knives and forcefields only. He gave us the why, and a half-hearted why-not for firearms and rayguns, and then the bit about how Rabban was given some classic ballistic artillery to surprise the Atreides with, but ultimately the concept of entire field armies fighting was left awfully vague. Which is what we see in the movie, too, with tactics-free slashing and stabbing between two or sometimes three mobs.
But Villeneuve tries - there are delightful visuals to establish that which cannot and really shouldn't be told in boring words. Spaceship-killing bombs or breaching pods that first drop down and then slowly force their way through the shield are really cool, and sort of the film's equivalent to the mere paragraph that Herbert originally gives for describing the fight and the future hardware used in it. We also see handheld and shipborne lasers, and they are scary as all hell, cutting through stone like butter. No ballistic artillery in evidence as such, alas.
Also, it's a brilliant choice to portray the forcefields as blue when stopping fast-moving threats and red when being penetrated by slow-moving blades or needles or the like. The audience can immediately tell what's going on, in duels or melees or ship-to-ship fights alike.
As for ecology, Kynes dies a bit differently in the film, and rather cleverly IMHO. This eliminates a chance for her(!) to have this long inner-monologue exposition about the life cycle of the shai-hulud, but we'll get it in the second movie one way or another, if we get the second movie at all.
All in all, Villeneuve chose to make the absolute minimum of choices, and IMHO made good ones, including the one to make so few... Whether this backfires when/if we get to view the duology as a whole remains to be seen.
Oh, and Shadout Mapes is in the film. And goes through all the motions, being in all the scenes that Herbert offers. She's cool when first facing Lady Jessica, yet not a presence but a prop in all the rest. We don't really learn anything about the Fremen through her past that first scene. Which is another of the good choices, leaving more for Kynes and later Stilgar to do on that front.
The Fenrings are not. Nor is there the slightest glimpse of the Emperor, which is another thing Villeneuve does better than Lynch: the Emperor is menacing rather than a puppet, and the heroes and the audience are yet to learn otherwise. Naturally no Irulan yet, either.
And no Feyd-Rautha yet, even in dialogue. Which makes sense since there isn't a plot function for him yet - but this IMHO is the one borderline bad choice in the film, as this anti-Paul does serve a significant function in the overall story, and could have done his foreshadowing bit for the King and the Country, or the Baron and the House. But there may be good and practical reasons for there being no actor for the part yet...
Timo Saloniemi
