I use a lot of different smartphones, but I very rarely use a case or screen protector. I prefer to keep my devices "naked," so they're as slim and as sleek as possible. However, a recent experience with my brand new Samsung Galaxy S III should serve as a cautionary tale for GS3 owners who also tend to spurn smartphone cases.
Behold the current state of my Galaxy S III. Note the smashed display. You can't see it in this particular image, but the entire screen is spiderwebbed. The slick, slippery device slid right out of my pants pocket as I exited my car, and it landed on its edge on the sidewalk. All it took was a drop from less than two feet. Smash. RIP GSIII. (Gorilla Glass, my ass.)
I really liked that device, too.
I've dropped countless mobile devices in more brutal ways than this, but the Galaxy S III's display is the first I've ever smashed. The Galaxy S III's screen is so large, and its casing is so slippery, that it is particularly prone to this type of damage. So, do yourself a favor and get a case for your Samsung Galaxy S III, even if it's just a rubber skin.