This module is awesome, I regularly use it to clean up Perl code. The API can be a bit daunting at first: it has many options and flags, however reading the tutorial (perltidy.sourceforge.net/tutorial.html) helped a lot.
This module is great! Not only does it nicely format code, it does an excellent job of telling you where your syntax errors are. If you've ever spent 5 minutes looking for that unmatched brace, bracket or parenthesis--you needed Perl-Tidy.
Having inherited a few large chunks of awful Perl, I first spent an hour or two running through the code and fixing indents, newlines, and other garbage like that. It sucked the will to live out of me! People kept talking about Perl Tidy, and I kept thinking, "Great, now I can make my code look like what somebody else wants." Once I finally bothered looking at it, though, I found that it could be configured to make the code look almost exactly as I would've written it!
It's extremely configurable, and the documentation is fantastic, including a Choose Your Own Adventure-style quickstart. Every maintenance programmer needs Perl Tidy.