Oh neat, I read the paper back of this book maybe two and a half or three years or so ago. I enjoyed it quite a bit. They do a good job at keeping tests a first class topic and consistently updating them with each addition. Some older architecture books don't treat testing as being as high up in their priorities. I've just found that having tests ready, easy to write, and easy to update, makes the development process more enjoyable for me since it's less manual for running the code to check for issue - tighter feedback look I guess.

I will say that some of the event oriented parts of this book were very interesting, but didn't seem as practical to implement in my current work.