Preordered this book and just finished reading it, and while it's an interesting read with lots of credible technical detail and a very believable alternate history in which Apollo 18 did not get cancelled, I'm a little disappointed also. Three main disappointments:

1, as a whodunnit it's extremely obvious whodunnit almost from the time of the murder. The death happens on page 80; they realize it wasn't an accident on past 125; and by page 151 it was pretty obvious who was responsible, even though the protagonis doesn't figure it out till page 425.

2, it's just not that well written; it's okay, but clunky, the type of writing that you learn to read the story through, rather than the type of writing that sucks you in and makes the story flow naturally. Far too much jumping around between different characters and different scenes within the first section; forced descriptions of characters, e.g. "he looked in the mirror, assessing what he saw. Six foor, 173 pounds (need to buy a scale), dark chest hair, pale skin..."

3, the protagonist Kaz Zemeckis is in a senior advisory role on the Apollo 18 project and meets various members of the flight and science teams when he arrives at the base. Among them Laura, an attractive geologist he rapidly learns is trying to learn to fly in order to qualify as a future astronayt, but having trouble affording the lessons. Almost immediately - their second conversation I think - he invites her to come over to his house where she can try flying his private plane; and it's made very clear that he's offering this because he finds her attractive, not because of any altruistic intent or feeling of camaraderie or wish to help less privileged minorities qualify for the astronautics program. No, he invites her over for exactly one reason, because she's pretty and he's lonely, and sure enough after they get back to his house after flying he puts the moves on. This is, unfortunately, probably a pretty reasonable depiction of how things would have happened at the time (1970s), and any woman in a situation like poor Laura was probably frequently in a situation where she was being dangled offers that would progress her career but which came with hopeful strings attached, and must have had to constantly navigate between them. What I found distasteful was less the facts of the era, and more that the author writing this in the 2020s wrote it so completely matter-of-factly as if the protagonist's actions were something he found completely normal and would have done himself. There was no apparent awareness of Laura's perspective or situation, in fact we never really see her as an autonomous person at all, only through Kaz's eyes. While there's no sign she's uninterested, there's also no sign she's interested; in fact there's no sign she's a real human being at all, because we only see her through Kaz's assumptions based on his own expectations. Just left a distasteful taste in my mouth.

Despite the above, it was still an interesting read, and there were some details of the plot that were interesting to see how they turned out. It wasn't as suspenseful as Andy Weir' "The Martian" nor did it have as much humour, but insofar as it is a reasonably scientifically accurate story about space travel, if you enjoyed the one you may also enjoy the other.