A short, elegant time travel novel. I appreciated that the characters were aware that their ability to change the past in small ways without radically altering all of subsequent history makes no sense, and that they proposed the simulation hypothesis as a potential explanation. I also liked the observation that a time traveler would need to intensively study everything about the place they're going and the people they'll be interacting with for years before making even a brief excursion into the past. The idea of using time travel as a cheap way to imprison people was amusing too, though I'd think the risks would drastically outweigh the cost savings.
One of the novel's themes is the importance of seeing the beauty in transient experiences:
There were dozens of trees up here, in enormous planters, with little lights sparkling in the branches. Music was playing somewhere, a string quartet. Olive was wearing her designated fancy tour dress, which was silver and went to her ankles. This is one of the glamorous moments, Olive thought, filing it carefully away so she could draw on it for sustenance later. The breeze carried a scent of jasmine.
Several times the book presents disconnected snippets of memories, not to advance the plot but for their own sake—it puts me in mind of "tears in rain" but with perhaps a more positive message: that whatever tragedies come after, the good moments retain their value.
A couple quotes I liked:
Won't most of us die in fairly unclimactic ways, our passing unremarked by almost everyone, our deaths becoming plot points in the narratives of the people around us?
There's a low-level, specific pain in having to accept that putting up with you requires a certain generosity of spirit in your loved ones.