This is definitely not a book for the Ajax expert. However, I didn't even know what AJAX stood for when I started reading this book, and it was definitely the book for me!
I wanted to add some basic "Web 2.0" features to a website I'd just created, and I didn't have much time to learn, so this book seemed a good choice when I saw it in a library.
Basically, it does exactly what it says on the tin. It gives brief, but not too brief, introductions to the technologies which make up Ajax, and gives you exactly what you need to know to get started. It's presented in bite-size chunks (which for me were a bit more than ten minutes, but maybe I'm slow!) which are pretty self-contained, and take you through Ajax in a logical progression.
By the end of Lesson 11, I knew enough to be writing my own small Ajax features for my website, and had them working fine in all the major browsers.
This is a small book, an unintimidating 200 pages in a nice portable format, which makes it easy to carry around with you. It's definitely aimed at Ajax beginners like me, and won't give enough depth for the advanced reader, nor go into subjects like the Google Web Toolkit, etc., but then it doesn't promise to.
What it does do is give an accurate and useful introduction to Ajax, including details on all the basic technologies, e.g. Javascript and XML and the way Ajax uses them. then carries on to give a taste of more advanced topics, including SOAP and REST.
For the low price, this is an excellent introduction to Ajax for people who know enough to develop simple websites but want to explore the use of simple Ajax features to improve the user experience.