I'm not sure you need to read the whole book to get value out of it. I'm not knocking the idea of NVC, I think it's helpful, however, reading the book it seemed like the author took a great article/blog post and turned it into a meandering book to jack up his speaking fees.

You can save yourself the time/money and just read the Wikipedia page - https://en.wikipedia.org/wiki/Nonviolent_Communication