Perl and Python have very different philosophies. Python is very focused on making syntax easier to read by forcing coding conventions to be followed. Perl on the other hand has gained a sort of reputation for being a "write only" language, as you can create some rather tight code which is unintelligible to all but the Perl interpreter. Realistically though, if someone comments their code adequately and has experience in the language, it shouldn't matter. But most of us (Perl programmers) like the freedom of choosing our own path.
in reply to Perl VS Python
It basically comes down to the right tool for the job. When it comes to messing with text, I don't think any language can top Perl, and of course Perl does many other things exceptionally well also - but on the other hand there are things which Perl is not good for. Believe me, if Perl loses popularity in favor of another language, it will not be because it's a better scripting language, it will be because it does Perl's job better than Perl. I see Python being a threat to Perl about as much as I see it being a threat to Visual Basic.