They did royally eff this up.
I think they made it more flash-like and colorful. I personally liked the simple setup, and I could find everything with no problem and without the frills.
Last night I went to watch a hockey game on there, and I had to download Flash Player and set it to 1200 kB bandwith because I couldn't even see the puck on 720 kB. Before the switch, I had no problems whatsoever. Boo to Yahoo.