I wanted to say that I've been forced technical books in the past and this one I was able to breeze through. I read the entire book in 3 days. It was a lot more thought provoking than any other technical book I have read in the past. I think the layout and the way topics were covered has a lot to do with the success of the book. I personally feel that there is a point of no return on subject matter where the R.O.I. is negligable for learning particular topics in a certain way. Head First Java really did well on finding that point and immediately switching the medium for which one learns.
For example, a topic might be introduced with a small paragraph merely discussing the topic at hand. Right as you get to the point the reader realizes they have no idea what the book is talking about there is an illustration, followed by an exerpt by your neighborhood 1980's good old boy...then swiftly it changes back to conversational discussion for a little longer. I'm willing to bet that much of the editing and revision for the book was trying to find the best times to switch learning mediums and which words needed to be emphasized. My only minor complaint is that the obscure theory pieces of the language that were left out or put in the appendix were not given the same attention. I suppose you were trying to avoid a 1300 page book eh?
I made this post because I wanted to thank you and your team for putting the work into not just content but also presentation.