The official reference for the Perl language did not improve in its second generation. The original "purple Camel" is, in my opinion, a true classic where books about programming and programming languages are concerned--I rank it right there with The C Programming Language, Anatomy of Lisp, Algorithms + Data Structures = Programs, and so forth. It was a classic because it was filled with lucid expressions of the thoughts of Perl's quintessentially pragmatic creator, Larry Wall. It was a classic because it provided a literate and thoroughly reasoned counterpoint to arguments in favor of more formally based languages and programming styles.
But ... somewhere in the extensive revisions, additions, extensions, and deletions that transformed the first Camel book into this, the second Camel book, the magic went away. And some very suspicious stuff went in. The book lost its digressive, essayic feel and became more of a perfunctory reference work. Additionally, some of the completely new material turned out to be just a little ... strange. The discussion of object-oriented programming based around the term "thingy" just doesn't do it for me. (Ignore all that and read Damian Conway's book instead.)
Preferences of style and tone aside, an unavoidable flaw of an infrequently-updated book like this one is that it inevitably refers to an obsolescent version of Perl. If you want current Perl documentation, you need to read the man(ual) pages that came with that version of Perl. What's in this book is generally but not completely accurate for newer versions of Perl. And because it's intended to be a more or less complete reference covering even small details, it can't help but be dead wrong on some points as the language continues to evolve. Bear in mind, also, that much of the material in this book comes STRAIGHT from the man pages. (Just not the up-to-date versions.)
A third edition is in the works, which will no doubt be at least a temporary improvement. If the newer version restores the insight and charm of the original, it will certainly deserve a place on your programming bookshelf. But as a reference work intended to cover a constantly-evolving language, Programming Perl will always suffer by being out of date.
If you are the type who dislikes reading electronic documentation, by all means, buy a copy of this book. But you'll find that you have to use the online documentation anyway.