Web APIs will become more and more interesting as they provide quick and easy access to data and functions from widely known web service providers auch as Google, eBay and others. However, this book can only provide an overview - "making the first API call". It is therefore useable for beginner s.
The book is easy to read, helpful for the first steps and conatins enough scripts and examples to understand the features and see the possibilities for extension.
All together, useful but not detailed.

This book does what I like in a book. Deliver great information on a specific topic without trying to be the do-all-end-all book. It focus's on API's with PHP and does a great job at doing so. Different chapters cover different API's with a catch all chapter at the end to cover additional popular API (like National Weather Service and Flickr).

This is the kind of book where its just fun to play around with and see what you can come up with.

I approached this book expecting a reasonably good tech cookbook with some code examples I could put to use. This book is that, plus more. The book gives a very good background of web APIs, plus thoughtful discussion about -why- certain items are done a certain way. For example, discussion about non-trivial security matters, and various reasons why you wouldn't want to produce a web feed (followed, of course, by how you would produce a web feed, in various flavors).
For me, this book very successfully balanced the dual goals "give me the nuts and bolts" and "tell me the background behind it all".
This book will not teach you PHP, so if you are a beginner, start with a more general PHP tutorial. Beyond that, I recommend this book.

The overviews are also excellent for concise functional descriptions that can be read by anyone with a general technical background. In sharp contrast to most technical books of this nature, this one is well organized, well written and very readable. It uses the PHP programming script/language to delve into specific implementation details, but the information can be readily understood regardless of the reader's specific language of choice. The material is presented in two sections. The first section in four chapters provides a general foundation in web services (or Service Oriented Architecture to use current technoabble). The second section in eight chapters describes specific uses and conventions for these services provided by the major companies of the New Economy, who are driving these technologies as engines of commerce. This field is an amalgam of several technologies, each with a huge supporting literature, and one of the more remarkable things about this book is the degree of editing it took to bring to the forefront those items that can immediately be used. Well worth the investment.

Those working on the PayPal services should also acquire 'Pro PayPal eCommerce' by Damon Williams as an excellent companion reference.Pro PayPal E-Commerce (Expert's Voice)

This book asumes you are already a programmer. There is no explaination of how to but rather a look at some API's out there. If you do not already know how to work with API's you will be lost. Of course if you already knew how to work with API in PHP you wouldnt have bought the book!