Perl is designed to assist the programmer with common tasks that are probably too heavy or too portability-sensitive for the shell, and yet too weird or short-lived or complicated to code in C or some other UNIX glue language.
Once you become familiar with Perl, you may find yourself spending less time trying to get shell quoting (or C declarations) right, and more time reading Usenet news and downhill snowboarding, because Perl is a great tool for leverage. Perl's powerful constructs allow you to create (with minimal fuss) some very cool one-up solutions or general tools. Also, you can drag those tools along to your next job, because Perl is highly portable and readily available, so you'll have even more time there to read Usenet news and annoy your friends at karaoke bars.
Like any language, Perl can be "write-only"; it's possible to write programs that are impossible to read. But with proper care, you can avoid this common accusation. Yes, sometimes Perl looks like line noise to the uninitiated, but to the seasoned Perl programmer, it looks like checksummed line noise with a mission in life. If you follow the guidelines of this book, your programs should be easy to read and easy to maintain, but they probably won't win any obfuscated Perl contests.