This is completely focused on the organization and I found it useless when moving from a Java to a Ruby team. Maybe if you're a consultant it's useful but probably by 2018 it's moot.

Give a good outlook on where Ruby currently stands and how one should approach a selection process where one chooses to use Ruby or some other language.

Not a book for people who want to learn Ruby, but for those of us who are curious about it and want to know how one might approach implementing it in a team it's a good read.

Good general overview of Ruby and where it's going in large businesses. My only beef is that it's already a bit out-dated. I would love to recommend a new edition of this book to all of the technical managers with which I work.