To me the main problem with Perl is that Perl6 is not fully implemented yet.
I'm not really trying to be sarcastic here. I really mean it. Perl5 is great but it is seriously getting old now. Now that I've started learning perl6, each time I write some Perl5 code, I really miss many of the cool features of perl6.
A typical example are ranges. In Perl6 when you want to write the integers from 0 to $n-1, you can type ^$n. Once you get used to such a shortcut, it's tough to keep yourself from using it.