Seveneves is the first Hugo nominee this year to defeat me.
I got about 70% of the way through, which isn't bad on a nearly 900-page book. But in the end, it really wasn't for me. Too much science, not enough fiction.
About 100 pages into Seveneves, I had the thought that I'd rather read a summary of the book than the actual book, and that thought only got more true as I continued. Seveneves has some interesting characters and a really interesting premise, but it's also full of diversions. It's like Victor Hugo writing science fiction, putting in large explanations of waste disposal on the ISS instead of in Paris's sewers.
If you like a lot of theory in your books, this really delivers. It takes a Big Idea -- what if the moon exploded? -- and follows what might happen next. Not "what does Protagonist do next?', but what might happen, scientifically speaking, and what could humanity achieve using science as a response.
I'm not going to make any claims about the legitimacy of the science here, because I don't know enough to judge. It feels confidently written, but it could all be confident mumbo-jumbo as far as I know. Most likely, it falls into that realm that's good enough for most readers, but contains enough slight issues that someone with a PhD in astrophysics would go "well, actually..." until their brain exploded. The book includes a lot of detail to convince you, either way. As a fantasy reader, used to the "well it's magic" explanation, I could happily have skipped all of it, and often did. As long as it doesn't contradict itself, I'm perfectly fine with handwaving.
But Seveneves is the exploration of that Big Idea and the science that follows, and so in that sense, the explanations weren't superfluous at all. It all depends on whether you want to read about What Happens After The Moon Explodes, or What This Set of Compelling Characters Does After the Moon Explodes. For the first, we need the science and the explanatory detours. For the second, they just get in the way. Unfortunately, I'm the second kind of reader.
So to me, reading Seveneves felt like being talked through a spider diagram. We start off on one solid topic, like the need to dock new ships onto the ISS. Then we step onto a more specific branch -- how does docking work in space typically, for example. Then onto a narrower branch -- how does it work on the space station specifically? And on and on, to more and more specific branches, until we've travelled really far from the story. Then the explanation is done, and we catapult back to the plot until another science fiction distraction pops up.
That said, Seveneves does have a plot. After jumping around a little in the beginning, it seems to settle onto two protagonists: Dinah, a robot-engineer doing research on ISS for a private company, who is quickly dismissed as Not Much Use once the moon explodes, and Doc Dubois, a celebrity scientist who realizes that the exploded moon will eventually bring about The End of the World. People have to figure out how to turn the ISS into a survivable habitat for humanity within two years, before everyone left standing on earth is wiped out, and these two characters are our main perspectives on the story.
But, ultimately, they're not the protagonists of the novel. Seveneves's protagonist is that hypothetical concept -- what if the moon exploded? -- and everything else is centered around that.
As a result, the novel feels somehow disconnected and plodding for a character reader like me. The story skips around a lot, skipping important character moments I would have wanted to read to instead focus on those scientific explanations. The nail in the coffin, for me, was reaching part three, which is set 5000 years in the future. Since the idea is the protagonist, it doesn't really matter in the novel that our previous characters are all long, long dead... but it mattered to me as a reader. Without any of the familiar characters I cared about, I lost any remaining reason to chug through the book's meanderings. I feel like I finished the book at the end of part 2, and even that was much, much too long.
Seveneves has an often engaging writing style, some interesting characters, and moments of true tension and drama. But those things are sparsely scattered over more in-depth theoretical thought, so although this might be a great book for hard science fiction fans, it's not one that I personally can recommend.