I haven't used a case for more than a day in a few years now, starting with my 5S. My jet black has a few scuffs on the back that only show in bright, direct light. I can't use it in even the thinnest Peel case. It's too nice to use with cheap plastic.
Heck, I even dropped it and got a small gouge on the top edge, and the only way I even know it's there is if I look for it.
I throw it on my desk, in my purse, in my pocket and it's held up much better than was led on at release. I'm very happy with it...and if something catastrophic happens, I have AppleCare.