An entertaining read for several reasons.
The most obvious one: The book puports to be a collection of various files, letters, other forms of correspondence, interviews - found footage, as it were, except it's not just found but has been actively collected and put in order. I like episolary novels, and this one runs with the design elements that the form allows. Starting around the middle, the book diverges from this principle, maybe adhering to the letter but not the spirit - we've got stream of consciousness from a major actor that wouldn't really be put down in the chosen form. Some experiments in typography follow (reminding me of Alfred Bester in Golem100 or The Demolished Man) that also break the pattern, but are fun to see/read.
Secondly, the plot takes quite a number of interesting turns. I hear they're making a film of it, it felt more like a TV show to me - season one gets its own baddie with its own countdown, and season two gets another countdown and another baddie.
Still, it's young adult science fiction, and I'm not a big fan and not the intended audience and don't watch TV shows all that much. But was Edmond Hamilton's space opera that I read as a teenager so much more adult? Probably not.