Advanced Perl Programming Second Edition should really be considered a completely separate book from the first edition. A complete rewrite by a different author covering different topics, this book represents much more the areas a respected Perl programmer should know about today than the rather aging previous edition. I'd hasten anyone who still has the previous edition knocking around to forget any idea they might have had about 'making do' with the old edition; So different are the two books that I'm keeping both editions next to each other on my bookshelf.
Despite it's title this edition of the book doesn't contain all you need to know about Advanced Perl Programming, but rather gives a simple introduction to several of the advanced topics that aren't covered by Programming Perl and it's ilk. Thankfully this scattershot of random topics prevents the book becoming bogged down in details and makes the subject matter accessible enough, imparting just enough knowledge to remain useful without becoming offputting.
I'd best describe this book as a quick way of finding out what you should be aware of and bootstrapping the process about learning about each of the topics. While there's no way that I could even hope to describe any of the chapters in the book as comprehensive, I'd say that they explain just enough that they give an idea of what you're trying to learn about without needlessly repeating the kind of information that's best to obtain directly from the associated module documentation and manual pages.
In addition to briefly covering some of the advanced topics, in some cases this book contains the best "dead tree" explanations of some of the more complicated aspects of Perl yet to be published. For example, the Unicode section in Programming Perl should probably be ignored in favour of the much more comprehensive chapter in this book that properly discusses modern Unicode handling as is used in Perl 5.8.
In conclusion, I highly recommend this book for any Perl Programmer who wants to move beyond the basics of using Perl to do simple tasks and wants to learn about the way Perl is programmed today.