The ACoupleOfAdmins blog recently posted a book review of the PowerShell Cookbook (and were kind enough to also write an Amazon Review.) They bring up some excellent points. Mainly,
The Windows PowerShell Cookbook will stay on my shelf as a reference book (for the code samples), but I would look to other resources first (e.g. Windows PowerShell In Action by Bruce Payette), if you need a resource to help learn PowerShell.
I thought long and hard about the depth and breadth of the book. One theme they're picking up on is that the PowerShell Cookbook is not a language focused book, and does not go into gritty detail about each language feature. This is intentional, as I wanted the book to have a very clear and unique value. We already have one PowerShell in Action, so there's really not a need for another.
One thing that's missed by the review is the implicit False Dichotomy -- that you should only have one book on PowerShell. The PowerShell Cookbook is intended to be a reference book (for its code samples and pre-packaged solutions,) while PowerShell in Action is intended to be a guided PowerShell tutorial. There is very little overlap between Bruce's book and the PowerShell Cookbook, and both provide significant value.
Since both Bruce and I wrote books with the intention to benefit the PowerShell community, it would not be in the best interest of anybody to have competing books!