This book will not teach you Japanese. It will teach you *about* Japanese. Though the description suggests it's beginner-friendly — and it is in fact even readable by those who speak no Japanese at all — it's most interesting if you can speak the language and find the idea that the use of "desu" and "masu" was a contested topic not very long ago, to pick a random example. If you're interested in linguistics and society and how the two intersect, this is a fascinating time capsule into the post-World War II era, when people started asking questions about what to do about the Japanese language itself.