I'm all for BBCode. It's reliable, simple, and like Jem said, it is one less thing to worry about. Moreover, I haven't seen many posts on the forums that can't be done in BBCode.
Bugs: Found some kind of weeeeeird template issue. I'm in IE7, WinXP. When my browser is not maximized here, there's an extra column between the forum thread column and the recent links/control panel column. Not a major issue since it fixes itself when I maximize. It just looks funny and I don't usually keep my windows maximized when I'm at work (these screens are sodding huge)
Re: Input format: I much prefer BBCode to wysiwyg. One less script to go haywire and more assurance that when I put in a linebreak it'll actually show up.
Also, new screen layout in the forums deserves a thumbs up. Much better division of real estate for the material.