I hate it. I sat in a 2010 today in the dealer showroom. In person or in photos, the rear is miserable design. The competition, (camaro), looks amazing from every angle, so to have even one "debatable" angle is a huge problem.
I think Ford is falling into a design trap here. They clearly need the trunk to be huge to fit the huge spare tire. So, they using slight of hand design techniques to try and make the trunk look smaller. Its not working. The result is a very odd looking rear. Instead, I say they put in a smaller spare, or just stick with a larger/longer looking rear like in the 2009.
The rest of the car is spot on, and the interior is hard to believe. Ford has really nailed interiors in the recent models. I am tempted to upgrade to a 2010, but waiting for the coyote engine. I hope Ford changes the rear when they change the powertrains.