...none of the traditional legacy-passing schemes was going to survive the Hard Rain. There was no point in drawing up a last will and testament, because all of your possessions were going to be destroyed along with you, and there would be no survivors to receive them. [loc.729]
A book of two halves, unequal in many respects. Though it is always much easier to read Stephenson's novels in ebook form, I did wish for a physical artifact which I could cut and splice into a shorter, more balanced novel. Or, to put it another way: I was heartened when I clicked 'forward' after an especially loaded conversation between the protagonists of the first half and read the words 'five thousand years later'.
The first part of the book deals with the extinction of all life on Earth, due to the breakup of the Moon. It's a gripping tale of immutable physics and clashing personalities: very readable, well-explained, highly educational, occasionally witty. It does few of the things I've enjoyed in Stephenson's previous work, but it does some new things that I am in favour of. There are plenty of interesting, rounded female characters who exercise power and agency. There are some interesting speculations about the possible reactions of Earth's doomed population. (A revolution in education: what's the point of studying for exams that'll never happen?) There is definitely some swashbuckling behaviour, and some moving heroism. Also a population bottleneck.
The second part of the book is about what happens when the survivors -- there are survivors -- return to Earth. Despite some misgivings about the traditions and stereotypes which have grown up around the different bloodlines, and the sense of predetermination, I enjoyed this part of the book a great deal more, even though it doesn't have the same narrative drive as the first part of the novel. The worldbuilding, the social dynamics, and a sense of joie de vivre reminded me of Kim Stanley Robinson's Mars trilogy -- though Stephenson's characters are somewhat less prone to political theorising.
In that second part of the novel, the Epic -- a narrative composed of recordings from the events of the first part -- is omnipresent. Seveneves might have been a more balanced read if it'd started 'five thousand years later' and flashed back via the mechanism of the Epic.
Stephenson may well have foreseen this kind of criticism. At any rate, there is a line that sums up the novel's structure very nicely: "a nail-biter of an opening, followed by endless grinding tedium, slowly building to a dramatic final reel." [loc.7338] Your mileage may vary: the hard SF of the first two-thirds of the novel may be much more your thing than the social, philosophical and ecological speculations of the final third. And, to be honest, the final reel isn't that dramatic. (Where are the Martians, eh?) But Stephenson's afterword brought into focus what I liked about the last third of Seveneves: it's the realisation of SFnal tropes, the profound appreciation of planetary life, and above all the positivity.