My performance review is approaching and I have found it difficult to gauge as there are not many PERL jobs available in Brisbane.

First off it's Perl or perl, never PERL. It's something some people get quite worked up about :-)

As to how much perl experience is worth? That depends on who you're talking to and what you want to do.

It's a useful tool for many jobs, even if your primary role isn't as a full time perl programmer. Most unix sysadmins won't think of themselves as perl programmers, but it will almost certainly be a tool they use on a regular basis.