It's frustrating but at the same time inspiring for its willfull dismantling of the hero's journey.
Don't have that much more to add, frankly. I enjoyed the worldbuilding, the philosophizing, the dialogues that read more like something from a holy script than actual dialogues that could be had.
Frustrating: its male-centricity. It seems that all women's purpose in this world is to carry children. Except for the women that are witches (actually, even their inner life seems to revolve around childbearing). Also typical how Paul has immense power and foresight, having been emperor for twelve years, but he still has to wonder what emotions and thoughts lie behind Chani's blue eyes. He remains a man.
I think Villeneuve's films did a laudable job of transforming the women's arcs into something twenty-first century-ish. Though at times it felt dangerously close to becoming a shallow love triangle at the cost of Chani and princess Irulan.
Also a bit weird: all the powerful figures are so easily nudged to outrage. I thought we'd established that they became powerful precisely because they were in such exact control over their emotions.
It's less transcendental than the first book. But the ending still hurt me plenty.