Always rocked my iPhone's naked. Tried many a case, hated all of them. I was intrigued by the Bumper though, and got one (actually will have 2 on the house, thx ) and have to say, it's the first case I've ever actually liked. It seems like natural extension of the iPhone, love how it feels in the hand, and feel that the compromise between protection and aesthetics is perfectly balanced.
I wouldn't be surprised if I end up with it being naked at some point.