This is a weird book. I say that as someone who loves weird books. This one though is a special animal and its weirdness permeates through its plot, structure, and characters. Even the title is oddly specific and deceptively literal. This is the story of seven Eve's. But that's too close to spoilers so let's get back on track.
The majority of the novel is centered around a what-if scenario. The moon has been broken. No one knows how, no one cares, and the human race has to decide what to do about the end of the world.
The weird bit of this book, indeed the piece that most represents the author's style, is reading people struggling against the inevitable. The common American scifi story captures people struggling to succeed over great odds. The story of Apollo and Gemini and Mercury are full of people being exceptional in the face a goal that seems impossible. The story is Seveneves is about people struggling against Gravity itself. a there is no victory. There's only how much sacrifice you are willing to spend in order for the species to survive. There a many examples of people trying to come to terms with their own death in the face of species survival. Success and failure measured in millions of lives. Lies told to have the status quo held stable long enough to try and save someone. What acts of evil are you willing to commit in the face of total extinction?
It's fascinating, and ends with a conclusion so insane you wonder if Stephenson lost faith in the rest of us at some point in the writing of this novel.
The last quarter of the book is really a short story about what happens after the end of the world. totally disconnected narratively, I think it was the author's attempt to inject some hope into the bleak tale he'd crafted and it works to some extent. Overall I enjoyed the book, but I think you need to come to this story with a lot of your own optimism for the future stored up to keep things level, or it might bum you out seeing just how petty and stupid and heroic and self sacrificing and wonderous humans can be when they hit the limit.
Seveneves gets four stars out of five.