Thanks for the thread!
I liked it, but I do have some problems with the world building and the plotlines. Mostly though, this is the second or third time whatever problems there are have been solved by the alien whatevers. Laconia gets most of its power destroyed by the anti-ringers, and Duarte is taken off the table completely by the same thing. The evil doctor gets destroyed -- and the power base shifted -- by Duarte using some sort of telekinetic superpower thing he hadn't shown before. Amos is resurrected by the zombie-making dogs. And given what we've seen of protomolecule technology, I've got no idea how the standard weapons of the Sol system were even able to take out the building platforms.
On a character front, I didn't love how Trejo, who has been shown as a sort of noble-but-obedient soldier, quickly stepped in to become as Draconian as Duarte. Likewise with Teresa's tutor, who just became bad for no real reason. And I would have liked to have seen what exactly the rebels were rebelling against. The book said that most things were left alone -- the Laconians put in rules, but for the most part the different parts of human civilization were on their own, still. That had been the case since the books began, except with different overlords, so why were so many so eager to force out Laconia? It would have served us to see some reasons for the kind of displeasure that builds a rebellion. Laconia was, in the end, just an extension of Martian philosophy, so i would have liked to see that displayed a bit more -- I would think Duarte and Laconia would be very popular, especially with the chip Mars has always had on its shoulder.
Also, one of the things Avasarala said when the gates were proven harmless was that this was the end of the dream of Mars -- that the presence of real worlds would take away the idea of terraforming the planet. I would imagine it would have made life in the belt different, too, that they had places with actual sky, oceans and gravity to live. So I wonder how popular the belt remained, even before Laconia. And did Laconia then try to force migrations? Just a bit of the universe it would have been good to get some better understanding for.
On the plus side, I would not have though Holden had that kind of cruelty in him toward Teresa, but it was a very cool move. I was sort of surprised that there wasn't any Holden/protomolecule/Miller interaction -- with so much of it nearby, Holden would have been a contact point I'm surprised they avoided. I liked Teresa, as sympathetic as they were making her, had the arrogance of a princess. That was a good trait to build in and one that could have been ignored by pushing her one way or the other.
Bobbie went out well. Original Amos not as much. And as they go into the last book, I've got no idea who they'd ever think to even stand up against someone who could just make a star go black hole. Duarte's idea at the end of Persolopis -- "storm heaven" -- was proven to not only be futile but disastrous. So i don't know what ZombieAmos was suggesting Holden do at the end Tiamat. Humanity's only real chance is to lay as low as they can for a few millennia and hope everyone can just get along.
None of these are great works of art, but I thought this one felt rushed, like they were relying too much on magic instead of really working out their characters and stories. They needed a book between this one (but they also needed a book between the last one, too). I imagine they're a little tired of the story (can't blame them), but I do hope they take a deep breath and really work at closing it out instead of having unknowable aliens save the say again.