There's a point when using devices, that I stop being so protective and just use the product with it's sleek design in my hand. I hate the feel and look of using cases with the iPhone because it is just do damn beautiful, why cover that up?
I do use a case right now, but that's because I just got the device and am a little scared that I'll be coming out of the car and it'll slip out of my pocket, a friend hits it outta my hand, the list goes on. However I am eventually going to move to the invisible shield on the BACK to protect it from some dings, as that is how it is set down. I just love the feel of using the natural design of the phone, and it's like two people on my shoulders telling me case or no case.
With the AppleCare that protects against drops, and the shield to "prevent" scratches, I'll make the switch soon.