I'm not a big fan and can't say I really got very much out of this book, perhaps because I have already been using nant and Cruise Control.Net, so much of the material wasn't new to me.
I was disappointed both by the book's lack of polish and the author's style which I found to be verbose and opinionated. There is too much made of the author's `process' and a strange habit of referring to developers as if they are apart from, and unwilling to partake of, an automated build process.
For me, one of nant's key points is that you can declare each target's dependencies (like a make file), so it can be asked to provide a mid-point target or several final targets with equal ease. Unless you follow the advice given in this book and chop your build process up into independent lumps.
The author also fails to separate the build from the environmental configuration and so deployment concerns (database names, server names, etc) creep into the build process. This is a big mistake in my view. A build process should produce a build. It should have no knowledge of the target environments the build ends up being deployed into.
On the other hand, it's fairly comprehensive and includes chapters on creating your own custom nant tasks, code generation and automatically upgrading databases. I wouldn't follow the advice given for those last two, but it is good that both subjects are included.
May be of use to a complete newcomer to build automation or a non-technical manager struggling with build quality issues, for example.