Jason Gilmore, the author, is as super smart guy: he was an editor of 1.5 of my books, and is a very clear communicator. (FWIW, he's also writing Ruby code; like me, he also finds that writing Ruby code makes writing *about* PHP code much harder.)
My original way of learning PHP was sitting down one weekend with a bunch of simple PHP and MySQL scripts and just hacking away at them. Reading through the code, understanding what it does. Removing variables. Adding variables. Copying sections of code to modify the existing code etc etc.
After a few days of this, I had the basics. enuff so that I could start building my own CMS.
Although, now that they have so many tutorials, I guess that helps a little more