Quick summary:Chapters 4 and 9 are excellent and may justify buying. Skip the rest.
The "hacks" format breaks the content of a technical book into (in this case 80) individual entries. As I mentioned in an earlier review, I like this format because like most developers I learn best by example.
Chapter 4 ("Power Hacks for Web Developers") is much better -- a grab bag of techniques that will have something new for most readers, even if they have Ajax experience. This chapter also benefits from multiple authors, as you get to see different stylistic choices being made. Also, this chapter encourages more thinking about "what can I do?" instead of just "how can I do it?" There are several examples of mashups that combine existing web services under a single Ajaxy front.
Chapters 5-8 cover a variety of Ajax libraries: DWR, Prototype+Rico, Ruby on Rails, and Scriptaculous. First let me say that I think the choice of which libraries to cover is spot on. The only obvious omission is Dojo, and Dojo is so big and ambitious that a chapter overview in "hacks" format would be useless. And that leads me to the problem: These chapters are not collections of hacks, rather they are introductory chapters that have been wrestled into a "hacks" format. All of these topics have much better coverage online and in other books (which I will be reviewing as this series continues).
The Rails and DWR chapters have particular issues: Chapter 7 (the Rails chapter) is way behind on Rails, claiming coverage of Version 0.9.4. Thomas and Hansson's excellent book
Agile Web Development with Rails
has a more up to date Ajax chapter, despite having a publish date that is nine months earlier. The DWR hacks (Chapter 5) miss almost everything that is cool about DWR. Hack #48 demonstrates accessing a custom object by having the object store values in a
Map and do its own
toJSON work. There is no mention of DWR's ability to automatically marshal real-world Java beans, which are typically not backed by
Maps. Hack #49 commits the cardinal sin of RPC, doing in multiple roundtrips what could be done in one. This is ironic, since DWR supports a batching operation which automates doing the right thing.
In summary: Intermediate to Advanced Ajax developers should read chapters 4 and 8, and beginners should read something else.