If you own this book you may never need another book about Perl.
"Perl is more than just a programming language, it is a culture. This language has a depth to the number of ways you can do things far greater than other languages and starting to use it is perhaps closer to learning how to speak a human language than it is to learning other programming languages." At least that's the impression that the book gives.
Even if that view isn't actually true, it certainly makes the language seem much friendlier and encourages you to use the commands you already know even if there are far better ways to do things. The book starts introducing ways to do things in Perl even while it is still explaining the basic building blocks on which the language is based so that even by the end of the first chapter you will be able to write working Perl programs that can perform significant tasks.
Following on from the initial overview of Perl the next section of the book takes each of the basic building blocks of programming languages in turn and explains in detail how they work in Perl and how that might differ from what you'd expect from other programming languages you might know.
If the book contained that much then it would be a worthwhile book. It doesn't stop there though as the next sections of the book go on to cover communication between processes, compiling programs, the command line, debugging, security, portability, and documentation, plus much more. That in turn is followed by yet another section that is a reference to Perl.
This book is basically two or three complete books on Perl all in the one book. You don't need one book to start learning Perl, another to learn the advanced parts, and a third as a reference as this book covers it all.