You can read more about the book on the page I made for it, and by reading Sitepoint's announcement page. There are also some sample chapters to download (OOP, APIs and security) to give you a taste. The digital editions are out already and the paperback version will be available on October 31st.
On a very personal note, this is my first book, and at times it felt like a mountain to climb. I love to write and to teach so the combination has been exhilarating and exhausting in equal parts. Of course, the release of the book is actually only the beginning, and I'm excited to be able to recommend it to people when I'm asked questions which I've already answered there :)