Hi, I'm the author. I actually just (soft) relaunched the book using a new backend, so the content's a little stale. Now that I've revamped all the formerly poor quality ebook generation I can focus on content once again.

Aside from not mentioning aggregations it should be fairly accurate, and is still a useful guide for a beginner.

I' hoping to revamp it to discuss aggregations over the next couple weeks.

I lost most of my disqus comments, unfortunately, when I relaunched the site last week as the URL structure changed. I revamped the book to have more content per page. It's probably a little less SEO friendly, but makes for a nicer reading experience.