For what it's worth, I have an old iPad Air that still gets a lot of use (especially recently, while I've been waiting for the new 12.9"). For its entire near four-year existence I've used it with the Smart Cover and nothing else, though I have a sleeve I'll put it in if I'm throwing it in a bag of other stuff. In four years of heavy use it's never scratched or anything. The Smart Cover protects the screen when not in use, and provides a nice grippy texture on the back when folded over for holding. And it keeps the whole package as thin and light as possible, which for me is a lot of the appeal of the iPad in the first place.