I started reading the Kindle version this weekend (on my iPad), and I'm really enjoying it. There aren't many books that cover FileMaker, so I try to read all of them as they are published. One of the things that I like about this series is that - as you mentioned - they don't present information in an encyclopedic manner. (The formatting of the Kindle edition is excellent, by the way.)
I'm often asked by clients that are interested in learning more about FileMaker if there are any "good books" that cover FileMaker, and for years I've recommended the Missing Manual series - going all the way back to the FileMaker Pro 8 version (that Susan wrote with Geoff Coffey). I'll be recommending the latest version to clients as well.
I'm not sure if Susan Prosser and Stuart Gripman will see this here or not (I hope so), but if so: Great job!