I don't know if you recall, Dolby, but you once added something I suggested on the old site. It was the little little footer at the bottom of the page that contained the forum path you were on, for example, "WoWInterface > Site Forums > Site help, bugs, suggestions/questions > New Site Layout feedback". It was a real time saver, since users are typically at the bottom of the page when they're done reading a thread and often want to go back a level or two. It's an especially big time saver for those who display the maximum threads per page; scrolling all the way to the top can be a pain for those folks. That footer didn't seem to translate over to the new layout, so I'm suggesting it again.
Overall, though, I really like the look. It does feels cleaner. I do agree that it's a tad bit dark and gloomy, though I'm not sure what exactly could be added to improve that. Perhaps have the section headers use a light background and dark or colored text? Dunno, just an idea.
And I also like the tabbed folder paradigm now being used. I've always found that more intuitive than a bunch of navigation buttons.