I'm going to say this prominently because I think it has caused some confusion among reviewers: This is a book by two nonbinary authors and the title is Life Isn't Binary, and it is NOT (primarily) about nonbinary gender identity! If you want a book that is primarily about nonbinary gender identity, this book may not give you what you're looking for!
Instead, it is about problems with binary thinking in all areas of life. There is a tendency for people to view many things in terms of two categories in opposition. Male/female and cis/trans, yes, but also Black/white, straight/gay, privileged/marginalized, body/mind, emotion/logic, friend/lover, us/them. The book examines and deconstructs these binaries and more, and encourages thinking about who currently benefits from their resultant flattening of nuance, and what we could gain from framing concepts in a less polarized way.
The book is short but extremely densely packed with ideas. I read it as a two-person book club with
I do think at times it can feel too dense and too short for the vast scope of its thesis. The authors can state in one sentence an absolutely massive idea that could itself be an entire book, and that's the only thing they say about it because they're already on to the next point. (The authors have in fact collaborated on several other books which sound like they may elaborate on some of the things where I was like, "so, that's all you're going to say about that one? okay!")
But I found the book very worthwhile and thought-provoking, and after returning it to the library I bought my own copy because I expect I will be re-reading it, referring to it, or wanting to lend it to people.