I needed a reference on Ant, and I decided to buy this one despite a negative review. The book is well-organized and well-written in a style that most developers will like.
The first three chapters do a wonderful job of introducing Ants capabilities and what you should use it for. I was already using Ant, but I learned a lot more about how I can make better use of it.
The fourth chapter is a reference of all the tags and how to use them. So far I have found that they are pretty accurate, and as an experienced user I assume that I can figure out anything that turns out to be changed (since this software is always subject to change) or even wrong.
The final chapters discuss advanced material, such as extending Ant with custom tasks, debugging build scripts, and setting up nightly builds. I feel that the book does a good job of explaining the how and why of these topics, too.
Overall, the organization of the book is similar to Oreilly's Unix in a Nutshell, where there are several chapters of reference material and a catalog of commands. I like that kind of book because it cuts to the chase for experienced users. Part of the reason I wanted this book was to structure my Ant projects intelligently, and I got my money's worth for that.