I think this book serves as a good intro to speculative biology and science fiction worldbuilding. If you are new to the genre (or are otherwise not a worldbuilding nerd like I am) I think it will certainly be an interesting read. Even as someone who has been consuming a lot of worldbuilding content whether textually or through video, this is definitely an interesting and entertaining project.
However, there are a number of issues I found during my read through which made it difficult for me to fully enjoy the book. There are a number of glaring typos or mistakes which were hard to ignore. The design and layout of some charts, tables, and figures could have used some review to more efficiently convey what is to be illustrated. I found some story arcs a bit awkward, or cut off at odd points. I personally wish the author explained a bit more of Yaetuan language, phonology, and communication through the eras, maybe even using standard IPA symbols, so I could understand how words were pronounced beyond the occasional anglicized attempt at conveying pronunciation. Additionally, further exploration of historical cultures and individuals would have gone a long way to help me understand some of the species' history and cultural evolution.
Regardless, this book held my attention until the end. I was a big fan of the dives into individual Yaetuan's lives, my previous criticisms aside. The start and end of the book are the stars of the book in my opinion. Cline is definitely creative and certainly knowledgeable about speculative biology, and it comes through most in these sections. The illustrations are also good in my opinion. I hope to see a revamped version of this in the future!