I bought the Apple leather case with my 6s+, and used it for about two weeks before I put it in a drawer forever.
Bad:
- The lip around the edge is slightly higher than the screen, so it hinders side-swiping and invoking the app switcher via left side force touch, two things I do constantly.
- It's slippery as hell. Especially after it gets polished in your pockets for a few weeks. I dropped mine several times. It's as bad or worse than a "naked" iPhone.
- It's heavy. Not in the big scheme of things, but even a couple ounces is noticeable on these phones.
- Shows every scratch and water stain on the leather.
- Collects fine grit, which over time will etch your aluminum. I personally didn't use it long enough to experience this, but others have.
- Volume/power buttons are hard to press.
Good:
- Attractive case.
- Does offer some real protection.
Yeah, that's about it.