This is two years ago and things might have improved. But the ports system did not have that much software, I didn't like the feel of the keyboard, it's a huge heat sink (and then in cold NY mornings it would be cold to the touch when I started it), I didn't like the anti-alising, I didn't like the default terminal program (and couldn't be bothered to get a new one ... that was the point of getting a powerbook in the first place - all the supposedly annoying sysadmin things I wouldn't have to do). java support was horrible too (that might be better - and besides this is not a java crowd)
I didn't like all the proprietary formats for iphoto, and itunes either.
oh and yeah. I have a lot of mail. The import into Mail.app took days. It was ok after that. But once again, the mail files use a proprietary tagging system to know when mail is read and what not. It wasn't fun porting that back to maildir.
try ubuntu. you might like.