I've had mine since Oct 5 2011....14 months
Never used a case, never once applied a screen protector....even for a second.
My case is pretty much as scuffed up as it can get without looking abused. The case around the camera lens has a tiny chip, and the silver ring around the lens is dented in 2-3 places. The usb port has some wiggle room in it, and it sounds like there may be a few grains of sand or something in it. The screen has one tiny 1/2 cm hairline scratch in its top right corner that is just barely deep enough to see when the screen is on. All-in-all, after 14 months of daily HEAVY use on a job where I'm regularly in and out of construction sites, I'd give the gorilla glass on my D720 a 99.9% out of 100%....that negative 0.1% is for the small scratch I did get. Sorry, imperfection is imperfection....but that's not to say I won't tell everyone I know to buy a phone with gorilla glass....because I will