Is using skeuomorphic design ever okay?

Skeuomorphism is a dirty word in iOS and OS X app design, but where exactly does it come from, and what makes a skeuomorphic design succeed or fail? Christopher Downer of Realmac Software has laid out what defines skeuomorphism (roughly, it's a design that retains features of an older object, like an e-reader app that looks like a book), how it's been used over the years in software, and when it's appropriate. "Comfort," Downer says, "can make skeuomorphism a valuable part of an applicationâ€...