Try it out at <a href="http://perlcritic.com/" rel="nofollow">http://perlcritic.com/</a>. The feedback is usable - when the tool finds something to complain about, it provides a link to documentation explaining what it didn't like, and the way it "should be".
I used Perl::Critic a few years ago on a contract to demonstrate the code I had written was over 90% "Perl-Critic" compliant.<p>For the few non compliant programs I then documented why and what could be done next (in nearly all cases these programs hadn't been refactored yet).<p>The client was extremely pleased. So much so he asked me to perform a program audit on the complete Perl codebase he had ;-)