I prefer my iPhone to be naked. The iPhone 4 is a marvel of industrial design. It's the best looking phone out there --period. That's why I hate having a case on it. It also feels great in the hand when naked.
My naked iPhone, however, led to a cracked iPhone. On April 19th, 2011 --a date I'll never forget-- my beautiful iPhone 4 smashed into an ugly asphalt parking lot. The rear glass plate cracked. I got little pieces of glass stuck stuck in my finger when, in a moment of sheer panic, I tried frantically wiping away the crack.
Thankfully, the Apple Store only charges $29 to replace the glass back. As a result of the incident, I now keep my iPhone protected by a trusty Incase Slider.