I have seen that head first book as well as the ones for javascript, object oriented design and analysis, HTML and Java. They are a very slick and laid back type of book which can be great for people who often think most programming books are way too dry. They have nice pictures and some good info but I find the extent of their info a bit lacking. As you can imagine, a book with lots of pictures and such take a lot of space where good content and tables could be. So while it may help you learning the basics, it by all means won't get into the heavy stuff and give you a well rounded and in depth read.
I must say that one book that I have seen lately that totally rocks is Illustrated C# for 2008. That has some good stuff in it and comes with many visual examples and diagrams. If you read the content and not quite understand, you can look at the diagram and almost always you will quickly get the idea. I would have bought it this weekend if I hadn't already known most of the topics actually covered in the book. At about 45.00 CAD it wouldn't have been worth it for me to really get maybe two chapters of really new info. But I highly recommend it for those learning for sure.
The head first series is nice too, but like I said, if you want to master a language it can only take you so far.