Hot on the heels of someone asking what is the advantage of perl, here is someone asking what the disadvantages are. Here are some I can think of:

• perl can't run other languages:
  • JavaScript (actually there's a JavaScript module)
  • C (just use Inline::C)
  • Prolog (actually, there are several implementations, such as AI::Prolog)
  • Basic (Language::Basic)
• It can't build a project (ExtUtils::MakeMaker)
• It's inefficient (perlxstut)
• It can't make tea.
• This "perl" of which you speak might not be the Perl interpreter, but simply another program with the same name.