The crucial point here is - naturally after assuring that it works as expected - whether the code is maintainable.
- Did you understand it?
- Would you feel comfortable fixing a bug in it?
Perl programs have a tendency for looking like what a cat types by accident when walking on the keyboard. If this person knows how to write readable Perl code that fits to the team, this is actually a good thing.
Then again, you may want to teach him about regular expressions, but only carefully :-)
