I've been using NetBeans for Java development for a while and have been hearing about Ant all that time. I have kept away from it, but when his book came up I jumped at the chance to read up on Ant.
This book is an excellent book on an excellent tool. The book walks through a simple, but complete, Ant script and then launches into every facet of the tool. With so many things you can do it is quite a task, but one that the book succeeds very well at.
The layout is excellent and there is a comprehensive contents and index with an appendix of all the Ant Tasks also at the back.
One thing I like when trying to understand something is example output. I, probably like others, find it easier to step through code where you can see the output at specific steps.
The book is for Ant 1.5 so it is very up to date.£40 is a lot but it is a very good book. It would be an excellent book if it were a bit cheaper.