I was getting bad 502 Gateway errors all day yesterday. I managed to get onto the forum for about five minutes, twice. Also, from what I could see, a lot all of the BBcode from old posts got messed up. So I think it's safe to say they're still working on it.
I can't be bothered even trying to fix my signature, what with how complicated it was.
EDIT: And when posting or editing the page freezes and you have to refresh, so you can never tell if it actually posted or not, especially since the site is so slow at the moment. My guess is the forum is still technically in the process of being updated, but it's at a stage where it's actually starting to be usable again, so they made it available,