Saw it on a large, loud screen last night. Overwhelming visual and sonic experience. Didn't feel long, and was very enjoyable. They did not fuck about with the "charasmatic religious leaders are bad mmkay?" angle at all. Blimey.
I was underwhelmed by the character development though. Chani, Stilgar, Jessica are all firmly set in their ways from the early scenes (sceptic, true believer, schemer respectively) and don't really change or grow throughout. They could easily have written an arc for those characters where they come to hold extreme positions by the end, but instead the knobs are just turned to 10 from the off, which makes a lot of their lines very on the nose. Christopher Walken is stunningly miscast. He's Christopher Walken in everything he's ever in, and is no different here.
But that's about all I have for negatives. Everything else was fantastic. Some of the imagery is burned on my brain.
Seems all but certain that part 3 will be made, and that will be a weird one. It's basically a palace intrigue story, with no worm riding, atomics, or massed armies.