You will be able to donwload the book directly from the document above too.

I don't  think the book is 'perfect' (what book ever is?) and I personall wish we had been able to publish the book with a better scholarly digital infrastructure (XML, CrossRef, independent identifiers for each chapter, a github repository for the book and datasets etc.). However as I say in my preface the final document is the result of  a gigantic collective effort to do the walk of open scholarship, in theory and practice, and its publication is an achievement against all odds and lack of resources. It is a happy occasion to see it available online, for free and under CC-BY.