I often finish trilogies feeling disappointed. Thankfully, no chance of that here. 
 The Stone Sky reveals not only the last end of the world, but also the beginning of the end, and it's so much bigger than I imagined. 
 Take a world filled with hardship and hate. Take a world that has reinvented oppression over, and over again. Take a world that is horrible by whatever measure you want to use. 
 Now, given the power to destroy it, what do you choose? 
 It's about violence and struggle, It's about love, (but it's not a romantic love.) (view spoiler)[Lerna is removed rather abruptly at the end of the book, which surprised me with its suddeness, but didn't cause me any real emotional stress. On a related note, Hoa's love for Essun is an oddness I'm still wrapping my head around. (hide spoiler)]) It's about the love of a mother for her daughter, despite everything else. It's about the choices we make after being kicked in the teeth over and over again, and I love it. Love, conflict, and the end of the world. I'm trying to think of another book with such a strong mother/daughter depiction and am currently drawing a blank (if you have recs, let me know). 
 Something that surprised me: In the first book, I found Hoa kind of weird and creepy. By the time I wrapped up the series, I was significantly more attached to him (with caveats). 
 One of the oddest criticisms I've seen of the trilogy is that the atrocities depicted against orogenes are quite literally unbelievable. I don't find them so unlikely. History informs us that human beings are capable of great evil against each other, on a fairly broad scale, for objectively minor reasons. One doesn't have to look far at all to find proof of this. 
 For better or worse, I've read The Broken Earth over the course of about 3 months. Maybe I lost a little bit of tension between lack of long-term waiting and still-noticible time-gaps between installments, but while I am very satisfied with this final book, I'm not jumping up and down in over-hyped joy. (That's probably my mood; objectively, the only major criticism I can lay against the book is that Hoa's sections were a little info-dumpy). Overall, The Stone Sky is a satisfying conclusion to a well-built story.