+ It certainly reaches more of the players.
+ Easier to just focus on what you're interested in.
+ You get threads that just would not have stood a chance on the mailing lists(other games etc.).
- To some extent it seems to have brought out more people who just argue for the sake of arguing. We had those on the mailing-list too, but they seem to do more of it on the forum.
- Moderation is not as good as it was with the moderated mailing-list. That's probably one of the reasons why people who like to argue seem to get more of it done.
All in all most of the problems I see are due to lax moderation and no clear guidelines for it.