This book is grossly overpriced for what it is. The level of information is comparable to the reference card that came with a Perl book I bought years ago. It has more words, but the words are not more useful. For example, under "Smartmatching", there is a paragraph that is word-for-word identical with the online (perldoc) documentation, then a table which is less useful than the table in the online documentation, and finally a little "info" icon that refers you to the online documentation.
It's difficult to imagine a class of users who will find this book useful. If you have been using Perl for 10+ years and want to become aware of recently-introduced features (like smartmatching), the book's lists might be helpful. For anyone else, the book is really too superficial to be useful. Being a book, it's not as quick or convenient to consult as a reference card, but it doesn't have enough additional information to be worth the trouble of looking things up in it. For anything more than checking the existence or spelling of a keyword (elif? elsif? elseif?) you're going to have to look at a more detailed description anyway, so why waste time on this booklet?