I used it for a while on my Psion 5 a couple of years ago. It appeared to be fully functional (except that the list of supported packages was "short"). However I never really made good use of it because I had to launch all Perl scripts from the shell, and EPOC doesn't really work well that way (for me).

For me OPL (the Psion's in-built BASIC varient) with Macro5 provided a far better was to add extra facilities to EPOC. The integration with the rest of the system was better, and it was easier to develop scripts on the Psion itself (rather than needing a PC).

This was a few years ago however, if there is a better Perl on the Psion then I would be interested.

PS: I do make extensive use of the Perl Ref Guide on the Psion, I can't remember where I got it from (I thought it was here but I can't see it.