I have used a large variety of resources to learn perl. This includes books, websites, code snooping etc.
The problem is that like just about everything else, 90% of Perl books and Perl tutorial websites are rubbish. One problem that I'm very interested in is how we in the Perl community steer potential Perl converts to all the good information before they find all of the rubbish.
As far as books go. The wisdom of the Perl community is gathered in perlfaq2. Try typing perldoc -q book at you command line.--
"The first rule of Perl club is you do not talk about
-- Chip Salzenberg