Be be 100% honest I don't think the layout is as efficient or functional as it was before. I have to scroll way more now to get to the forum I want, when before the tree menu on the left was a quick couple of clicks at most to get where I want.
It's good that the theme matches the rest of the site, but the size and font plus fixed column layout make everything seem more squashed, in my opinion.
I could see how this layout would be more functional for different types of user agents, but as a standard layout not as good as before.
Also, there seems to be some weird word-wrap thing going on with this text box, and where are highlighted discussions? That was a great feature, I hope it makes it back, or maybe I just missed it in this layout.
Colour scheme is nice.
*edited for typos