Saw it last night.
It was a pretty awesome experience, especially in IMAX. Really blown away by the visual spectacle, the spot-on casting for the characters, and the performances. Insofar as the story and book vs. movie, it was all there, or at least all of the important parts that were needed to bring the complete story onto the screen. Just as in the first part, a few smaller details had to be left out, but it really didn't impact the plot in any way, and any viewers that didn't read the book won't know anything is missing, or has been altered, as is the case of the two major changes Kit has alluded to.
The first one is definitely a byproduct of the huge time compression between Paul and Jessica joining the Fremen, and the emperor's arrival on Arrakis, so it makes sense that it played out the way it did. However, there is a key moment that that missing character is a part of at the end that has greater implications in Children of Dune, but since there are no plans to take the movies that far, we won't really see that play out. As for the other change, one that fundamentally alters a major character, I was of mixed feelings yesterday, thinking that it did feel more appropriate somehow, but this morning as I think on it more, I'm catching more of a whiff of modern sensibilities playing a role in the change, and an 'update' to the character driven by a particular socio-political movement and ideology that pervades entertainment today. Nothing wrong with that movement by itself and what it champions, but its forced insertion into a classic work like this leaves me feeling disappointed for the author's intentions and creation because the character, as written was also perfectly valid and just as realistic in their path and personal choices. If Dennis gets to make Dune Messiah, it will be interesting to see how they will reconcile all that.
So, other than disagreeing with that one character change, all that remains are minor nitpicks, such as the removal of characters like Thufir Hawat and Count Fenring, whose scenes were shot but removed from the final cut, and the climactic battle at the end felt overly rushed. After such a huge buildup, it was either over too quickly, or they simply didn't show enough, at least to my satisfaction. We know that the Fremen ultimately prove better fighters than the Sardaukar, but after the latter were pumped up for the audience by showing how easily they defeated the best the Atreides had, they were practically a non-factor in the final battle. Guess you can't do much against sandworms, but the ground fight was over in a flash. Disappointing. Also, either I missed it, or when they were discussing the plan of attack, it was never mentioned what the atomics would be used for. Instead, we just get to see them launched and the subsequent destruction of the Shield Wall, but I'm sure many were left wondering why they weren't used to wipe out the vast majority of the assembled Sardaukar army and ships. It just felt... odd.
Lastly, I was looking out for the scene with the lasguns and the "No shields!" and good thing I was because it happens right at the beginning of the movie... lol. It comes and goes so quickly, I think most people won't even pick up on it, but yeah, a line or two to explain that somewhere would have been cool, from a techie-nerd's viewpoint. Interestingly enough, for the new Dune Awakening survival game coming out, the game designers had to go to the Herbert Estate to seek permission to do away with that particular in-universe rule. Why? In play-testing, they quickly realized that far too many players would 'break' the game by constantly and purposely inducing localized nuke strikes on each other.