omg I finally finished a non-fiction book, and a technical one, and this one in particular, at that! This book is excellent, really, but until I had learned some of the material piecemeal from my job and from watching talks, I couldn't get myself past the first couple chapters. I think also I had to come to accept that having to take breaks (and also possibly naps...) when reading programming books is just a thing for me.
Anyway, the explanations and examples are very good. I think I may finally understand the Ruby object model and method lookup process!!! I like that there's enough of a behind-the-scenes peek at why certain things are the way they are in Ruby, without bogging you down with excruciating detail. The framing narrative of pairing with expert Rubyist "Bill" is a little tedious at times, but he does mix in female pronouns here and there, so don't let that bug you too much.
I'm not sure how useful this information is necessarily for a straight up Rails developer, but if you want to understand Ruby the language better, this is great.