I also just started using Perl with Ubuntu. I had been used to installing modules from CPAN, but after a couple of failed builds (involving some modules with C code which reacted badly to my AMD_64 architecture) I decided to give the Ubuntu package manager a shot. It's definitely a nicer interface, rather like Activestate's Perl Package Manager -- you just install the pre-compiled binaries, with no worries about builds failing.

However: those nice pre-compiled binaries are not guaranteed to be built from the latest source available on CPAN, and they are not guaranteed to be compatible with whatever modules you've downloaded from CPAN. I had been using Hardy Heron, and ran into rather painful version compatibility issues with some of the SMTP, IMAP, and SSL modules. Upgrading to Jaunty Jackalope fixed the issues, albeit at some cost.

Bottom Line: The Ubuntu package manager is nice for installing pre-compiled Perl modules, but BE CAREFUL mixing those modules with modules from CPAN -- there may be version compatibility issues.