To be honest, I haven't actually read the book itself. However, I have read a fair few of Donna's articles on UX and IA, which I've blogged about in the past and the free chapter from her book is also well worth a read.
The free chapter is called 'Testing your IA':
You’re over the main hump of your IA design process. You’re happy with the IA you’ve come up with, it fits your content, and should work well for the users. Before you continue it’s a great idea to test that assumption. Instead of just thinking and hoping it will work for the users, make sure it actually will.Donna's publisher has gone bust, meaning her book is no longer available in print, but you can buy it through a couple of popular online sources, and if you want a PDF she's offering to give it away.
A practical guide to information architecture - free chapter and how to get a copy of Donna's book