...for those who already regularly use Perl you should already have this book!
This is a companion book to Larry Wall's "Programming Perl" (the Camel book). So if you have the Camel book, do you need this too? Yes! Whereas the Camel book deals with the basics of learning Perl as a language, the Cookbook is a collection of problem solving and examples in Perl. As a result it is not a book to read from one end to the other, which is possible with the Camel book, in teaching you Perl.
For the recipes within the cookbook to work, a good index and contents are essential to navigate you through it. Here the book scores well, with each chapter focused on similar areas, broken down into subsections. There is even an index of the example code fragments!
If you are interested in Perl beyond the Camel book, like most O'Reilly books, you ought to get this book. And for those who already regularly use Perl you should already have this book!