I don't like the new proposed look at all. Sure it's clean, but, it isn't very clear where one post ends and another begins. Maybe the colors just need some tweaking. I generally prefer a simple UI anyways, no need to gloss things too much. Then again, maybe it's just the way the forum displays on the OPs box, could look a bit different on mine.
And, I don't like the way the font looks. For all I know it's the same font, just in bold, but, it doesn't look good on the screen.
I am always one for change, so, this isn't me just being all "wah" about change, I just think the forums look great the way they are, and, the screenshot posted is in no way an improvement IMO.
I guess I'm okay with the moving of the quote/reply button and like/thanks button, but, I am disappointed to see the lack of multi-quote. :'(