Thanks!
It’s polished aluminum, so it does pick up some scratches at the highest point where the corners touch on the back. So far, the scratches on mine are fine, hairline type scratches. Think of the fine scratches that might develop on a ring, a metal eyeglass frame, or a watch case; so more like a patina than being unsightly. This won’t be an issue at all if you mostly lay your phone face down.
For me, not at all. At first I wasn’t sure about the corners bulging out, but they actually provide something to grip when taking the phone out of pockets, etc.