This book was fun, but it felt like it couldn't decide if it was a younger YA or adult book. The characters were well-sketched, but didn't have much depth and despite being adults often felt like teens; also, many of the sci-fi worldbuilding details felt like they were going for realism/plausibility, but most of those details actually made very little sense if you know too much about the scientific principles that supposedly backed them up. But if you are okay to not think too carefully about some of the worldbuilding premises of the story, you'll probably enjoy the story for what it is.