I use the "White" theme on the main forums, which is actually pretty similar to this forum, so I don't have any complaints about the current forum design taken on it's own merits. However, it's just different enough from the main site to be a bit disorienting when I come to this forum.
I personally would like to see this forum be consistent with the main forums. It just feels off to have the UI change for this one forum. I suppose if the plan down the line is to separate this forum from the main one, it doesn't matter, but as long as it's functionally a part of the main forums, I feel like it really should follow the same design.