I really like this book, it covers a lot of territory in a very practical way, while also digging into the "why's" of things should be done the way Michael suggests. Understanding the "why's" is important so that if you want your site to do something different, you can make a good decision about the implementation.
The book is also very "satisfying." I'm a deep technical person [...], though don't have much Drupal experience. I was afraid, I'd have to bite my tongue and toothpick my eyes open to read this book for the Drupal specifics. That's not been the case. It's an easy read, interesting, and relevant. I'm currently thinking about a few new social projects, and while I wouldn't go so far to say that you should read this book whatever platform you are deploying on; I would say that you should consider prototyping on Drupal with this book in hand so you could make a better platform decision once you know more about building a social site. (sorry about the run-on sentence!).
I gave it a 4 instead of 5 stars, because there are a few places where there are typos that affect the content, and other places where ideas are used before they're explained, or a final screen shot that brings it all together is missing. I realize it's really boring to read a lot of explanations, and then read about the example, and sometimes it's best to talk about the example, and explain stuff after. It just makes it harder to read because I'm trying to figure out if something will be explained later, or if I need to look online before reading further.
This book has saved me a LOT of time researching Drupal and its plugins on line, so really glad I'm reading it. There were a lot of good references for further reading about the topics discussed AND the topics referenced, but not discussed in the book.