Pro Ajax and the .NET 2.0 Platform, by Daniel Woolston, attempts to tackle three goals:
Fortunately, the author is well-versed in ASP.NET development and the idioms and practices that make for well-organized code. If nothing else, the final chapters serve as a good example of what clean, modular ASP.NET can look like. But it is very much better than that. The book provides a wonderful, ground-up walk through of integrating the major Ajax frameworks for .NET into your application. Particularly, he does a great job with demonstrating the marshaling of data back and forth between the server and browser, and dealing with the architecture of your handles/URLs on the server to deal with the non-standard request patterns in Ajax apps.
Less-(or perhaps un-)fortunately, the author also suffers from a common ailment in books of this genre: provincialism. The opening chapters of the book were riddled with examples of the author's lack of experience outside his chosen platform. I won't be a jerk and do a point-by-point analysis of what turned me off, but instead just provide three examples.
In the first chapter, as he is describing the inception of the web, he refers to the first browser as the "Mozilla" browser from NCSA. Three times. Could be a search-and-replace problem, but that browser was called Mosaic. Secondly, he admits that he shied away from learning JavaScript for many years because he just assumed it was Java, which means that he was dissuaded from even a cursory examination of the technology by four letters in its name. And, third, in his timeline for the history of web development, the second major event is "Bill Gates and Paul Allen create BASIC for the Altair". Which might be an important step in the history of ASP, but is hardly seminal for, say, all those people who wrote CGI apps with Perl. In fact, his history of web development only mentions one technology not produced by Microsoft: Netscape.
Now, this doesn't mean that the book is bad. It means, though, that the chapters on actual Ajax implementations are very, very Microsoft-specific. Sure, you say, that's fine, though. Its an ASP.NET 2.0 book, after all. True, but the lack of deep JavaScript coverage, or acknowledgment of alternate strategies, leaves a limited scope to the ideas imparted.
In all, I think the book serves one audience very well: developers who get paid to write ASP.NET code, and aren't looking around beyond their borders. However, I'd love to see a second edition of the book branch out and at least explain the alternate strategies, like incorporating Dojo or Prototype or Rico or some other non-Microsoft framework and really tackling JavaScript as a first-class programming language in its own right.
Overall, for its major purpose, I'd give it an A-. For its two lesser purposes (history and JavaScript), I'll give it a D. If you are starting an Ajax app in ASP.NET 2.0, it is an important book for you. If you want to place the ASP.NET 2.0 tools in context, look elsewhere.