Imho, it depends on your requirement - somebody wants to use own simple objects and somebody wants to hack everything :)
I read some 'man perl*' manuals and Advanced Perl Programing, by Sriram Srinivasan.
Good luck!
I second the suggestion regarding Advanced Perl Programing, by Sriram Srinivasan. It has some good stuff about OO and classes in Perl. Plus some useful examples.