(This refers to the 1st edition, hopefully the 2nd edition is even better)
Maybe it's that I started learning Perl with this book, but I continue to use it as a reference even when O'Reilly "Programming Perl" BIBLE is right next to it on my shelf. I haven't been able to answer why, but I think it's for the following reasons:
O'Reilly is great if you know the name of the function you want. I find Cross-Platform Perl to be better when you know _what_ you want to do, but can't remember the functions that do it. Titles of chapters are (or were) user-friendly like "Working with Files" or "Launching Applications". O'Reilly has chapters like "References", "Data Structures", "Objects" and my favorite "Functions" (which has 200+ pages of, you guessed it, Perl Functions).
Get this book if you're new to Perl - you won't outgrow it.