Seveneves is not a great book, and maybe is not even a good book, but it is an interesting book. The structure of the story is divided into two parts. In the first part the moon is blown up, which is good as far as it goes. Stupid moon. However, serious amounts of moon debris are scheduled to rain down after 2 years, meaning that anyone who wants to live needs to get off the earth and into space where they and their descendants can ride out the moon-rain. This is basically a thought experiment in saying "what if you had the entire earth's resources to devote to the space program, how awesome could you make the ISS in two years? Make sure to show your work". So if you like the ISS, or space, or astronauts, and want 500 pages obsessively devoted to that, then you will love this novel. I am only luke warm on space and the ISS, so as with Perdido Street Station, I ended up strategically skipping certain sentences and paragraph-parts. I mean, these things are interesting, but are they 500 pages interesting? (No.) I had particular problems from page 100 (after the initial premise had worn off) to page 400. A lot of this section struck me as silly, as they posit a world where 99.99999% of people will die in 2 years, and yet things keep more or less functioning up until the end. E.g. one of the main characters, a Neil deGrasse Tyson stand-in, takes a plane flight to see family near the end. And it implies all sorts of things like stewardesses, and pilots, and mechanics, and baggage handlers who are doing their day to day jobs despite the fact they know they are dying in a few weeks. And I just don't see it. Like I can see the moon blowing up, but I can't see people showing up to their minimum wage jobs the week before the apocalypse. I think the _Last Police Man_ had a much more realistic and nuanced take on this situation, of what sorts of things would happen in the rapid and complete collapse of values. Rick and Morty also did a good job with this scenario. Similarly, I think the idea that there would be a global, rational response to the crisis is rather far fetched, especially the idea that elites would agree not to send themselves up. But anyway, that is the author's conceit, so we will just ignore that and focus on the science. And it does actually start to pay off. Around page 400 the story starts to get legs again, carrying things straight up to the page 500 boundary.
And that's where the second part of the story begins. I don't want to say too much about this second part, but it is almost like a review or reflection of the first 500 pages of the novel. Handmaid's tale did something slightly similar, where you have a normal novel, and it is bookended by ~10 pages of anthropologists talking about the novel. Seveneves takes this ~10 page bookend, and expands it to 300 pages, reviewing and reflecting and transforming the first 500 pages of the story. Another comparison would be to a Legacy game, where you first play one game, and then you play the second game based on the configurations and ruins left by the first game. Admittedly, the second game/story does just kind of wander and not really go anywhere or come to any conclusion, but structurally at least it was delightful. I don't want to say too much more about this, except that if you are going to read the book you should do yourself a favor and not read any detailed reviews (except mine) or even the book-jacket. Just dive in blind to this one.
So! The book has neat bit parts, and neat ideas, and semi-neat characters, and some funny moments, and some clever moments, and some smart moments, and some structural ingenuity, but waaaay too much science detail and a lack of any really coherent plot arc and a somewhat blinkered view of human beings. It's also 820 pages. :) If nothing else, it would make effective radiation shielding?