I’ll give that one a so-so rating IMO. It took forever to reach the inevitable catastrophe, it really felt dragged out. However, I found the post-event culture, technology, and societal groups fascinating…and as soon as things got interesting he ended the story. I’d gladly read a series about those cultures, there was tons of room for worldbuilding.
(Sorry about the indirect wording, I don’t want to give up any spoilers)