look elswhere
This book is very thin on where you need it most. For instance, only the very very basics of SCR is mentioned. They do not even mention how to restore SCR. Try another book. Add-ADPermission, a command that is commonly used in Exchange, is not even found. A thick book, but nothing really covered well. Maybe a good book if you are brand new to exchange, and want something to read from cover to cover. You will be left in the dark if you use this a companion.
E2K7 Admin Companion - essential
working with Exchange 2007 (E2K7) since July '07 and Exchange (5.5 and 2003) since 1999, i am somewhat familiar with Microsoft's Mail products. the E2K7 takes it to another level and this book gives you the info you need. is it the best and the only reference you will need? no, certainly not but it IS a good place to start. PowerShell is very pervasive and the more you know about it the easier your life will be as the EMC (Exchange Mangement Console) is not the same thing you got in the last version Exchange 2003's ESM (Exchange System Management). my suggestion is to pick up a PowerShell SP1 book, i reviewed a great one recently and i have about 5 so far.
Bottom line, good book to have but you will need others especially concerning PowerShell. i own about a dozen of the Admin Companions and their Pocket Consultants as well.