Rating: 

The negative aspect of this is that you have to go through more pages than usually to learn about the same amount as covered in other books.

though...

You have to think about the purpous and the approach of the book! It implicates knowledge of which you will even be aware of years later, and thus the book has a long-lasting effect, every other book simply cannot and will not provide!

Of course, if you would like to dig deeper into the matter of AJAX and you're looking for comprehensive stuff, this shouldn't be your first choice and it will certainly not fulfil your needs.

but...

In spite of exclusively covering the basisc this book will give you a fundamental basis of knowledge about the whole AJAX thing.

My personal conclusion is that AJAX Head Rush book totally lives up to its promises and I highly recommend it for beginners.