I can't help but think if perhaps you have decided to learn it, rather than explore it, maybe your opinion would be somewhat different.
What I mean by that is that at first glance, Perl looks very similar to some other languages, but the difference in design philosophy means it often behaves in a different way than you would expect from Python, or even Ruby (which borrows quite heavily from Perl). I doubt you would jump into Lisp coming from C or Python without a good guide, because Lisp looks different. Perl doesn't necessarily "look different" (beyond sigils, but that's usually just waved away without thought), but it is different in many ways. In that respect, Perl can sometimes be harder to learn for someone who already has experience in other imperative languages, such as C or Python.
What I mean by that is that at first glance, Perl looks very similar to some other languages, but the difference in design philosophy means it often behaves in a different way than you would expect from Python, or even Ruby (which borrows quite heavily from Perl). I doubt you would jump into Lisp coming from C or Python without a good guide, because Lisp looks different. Perl doesn't necessarily "look different" (beyond sigils, but that's usually just waved away without thought), but it is different in many ways. In that respect, Perl can sometimes be harder to learn for someone who already has experience in other imperative languages, such as C or Python.