I reviewed the first edition and gave it 5 stars on amazon.com. I still like the style used for the 2nd edition. The 2nd edition covers PowerShell 2.0, which is due to be released along with Windows 7 around October 2009.
The 2nd edition has about 40 pages more content.
I would only give 4 stars for this second edition. This book is based on the CTP2 release. A few major things that changed from CTP2 to CTP3 is that the *-Runspace cmdlets are now renamed to *-PsSession, and *-PsJob cmdlets have also been renamed to *-Job.
Some of the prerequisites for PowerShell v2 are also a bit unclear. If one is planning to use the new PowerShell remoting or the new PowerShell Integrated Scripting Environment (ISE), the book doesn't cover the prerequisites in enough detail.
Even with the above comments, I would still strongly recommend this book to a PowerShell beginner.
NOTE: Amazon.com has changed its review policy. I can only submit a review if I purchased the book from *them*. I typically buy my books from stores or chapters.ca.