I expected forums to be used for feedback, questions, etc., but maybe something more structured would be good. Following the dev.tw.o pattern, it would probably be good to use Trackers. To keep themes stuff in one place, we could set up a Tracker here for theme bugs. I sometimes lose track of specific problems with themes, so this would probably help me, for one.
A problem is that images seem to still be a problem in Trackers, or at least that's been my experience. So maybe Trackers plus an image gallery for visuals would be good. The forums are still there for related discussions.