I like the look. The operation totally bites though. As a primary example, it annoys me to no end that your collection of ads requires me to hit the back button on my browser multiple times just to move back to the last page I was viewing.
I'm also not terribly fond of the required tab navigation. Before, we could simply scroll and see all of the forums, but now, the confusing naming of your top level categories smacks us in the face while it could be ignored before. The only categories that give a good idea of what they deal with are Software Dev and Web Dev.