You have to make your own sidebars now. Personally, I never liked the sidebars anyway because they just took up space. I guess instead of having one extra column that was easy to get rid of, we now have two extra columns that we're stuck with.
And there's no "Find in Forum" link, and no search box at the top of the page. And it loads incredibly slowly.
Other than that, and the color, I think I can live with it.