I bought this book and passed up the official Microsoft text (Willis/McLean) due to a bad experience with the previous official Microsoft Exchange book written by the same pair.
I think doing so was a mistake.
I worked my way completely through the Schmied/Miller text, did all the study questions, and at the end redid all the study questions and then took the practice tests included on the CD-ROM. At that point I still felt unprepared for the exam, so I bought a prep kit from MeasureUp for $70 and carefully followed MeasureUp's prep procedure. Finally I felt prepared and took the exam.
I failed with a 667 out of 700.
Now, this was my fifth exam. I've never before failed one. In fact when I went in I felt very confident and was not at all worried about passing. How wrong I was! There were probably between ten and fifteen questions on the 70-236 exam that I flat did not know the answer to, and most of those I was not able to answer even through process of elimination.
Now, before you accuse me of inadequate preparation, keep in mind that I had been preparing about three months for this exam (reading the text, going through study questions, etc). In addition to that, I've been an Exchange Server 2007 admin for more than a year. I thought I was ready. I absolutely was not.
The fact is that the exam focuses entirely on PowerShell. There are absolutely NO questions having to do with the GUI (Microsoft Exchange Management Console) on the exam. And the Schmied/Miller text, while emphasizing that PowerShell is important ("some of these commands are likely to make an appearance on your exam"), does not stress this.
Schmied and Miller have written a lot about using the GUI to accomplish tasks but for some reason leave the equivalent PowerShell commands only as an afterthought. The emphasis is completely backwards -- this book should drill PowerShell into your head and minimize the GUI material. For a Microsoft admin who has grown used to doing things the GUI way over the past fifteen years, this is a particularly hard concept, but it's the way things are going.
In short, while I can't say that there is really anything wrong with this book per se, it is woefully inadequate if you want to pass the 70-236 exam. Buy at least one other book and make sure you dream in PowerShell code at night before you think of taking this exam. Take my word for it, 70-236 is a very challenging exam, and every minute you spend preparing for it will be worthwhile.