That depends on what you want to do. If you want to do things with text, especially transforming text, Perl is IMO opinion better at that task. Perl has been the scripting language for me, but I'm thinking of changing to Python because of NumPy, SciPy and the libraries for numerical analysis and scientific computing. Python seems to be better than Perl in that area. This is a library issue whereas when it comes to text processing it's more of a language thing.
I think Perl and Python have a lot more in common than differences when it comes to what they are good at. If you know one scripting language, you don't gain as much when you learn the next. My recommendation is to learn something different, C, Haskell, Lisp or Prolog for example. That would make you think in different ways.
Also, chromatic (a Perl developer) gives a very balanced answer in a sibling to my answer, so I won't repeat what he said.
If you want to stick to perl, you might want to check out http://pdl.perl.org/ if you haven't already. You can do a fair amount of scientific computing with it.
Among other things it overloads the basic operators, so $a+$b will do the right thing, even if $a and %b are matrices/images, so it is very easy to "read" if you are a perl person already.
I think Perl and Python have a lot more in common than differences when it comes to what they are good at. If you know one scripting language, you don't gain as much when you learn the next. My recommendation is to learn something different, C, Haskell, Lisp or Prolog for example. That would make you think in different ways.
Also, chromatic (a Perl developer) gives a very balanced answer in a sibling to my answer, so I won't repeat what he said.