I've been extremely careful with my S3 stainless - unlike the S0 it replaced, it's never been smacked against a wall, never been worn on the beach, etc ... and yet somehow it has about a half a dozen tiny (but DEEP) scratches in the sapphire (after less than a year of ownership - my S0 OTOH was absolutely perfect after 2.5 years) ... I'm happy to post pictures (again) but yeah - very disappointed in the strength/durability of my S3's sapphire. Still ordered a stainless steel S4, lol, because if Apple's current "sapphire" scratches this easily, I hate to think what that Ion-X Glass would look like after a year of daily wear.
ps. before anyone else says 'they're probably just scratches in the oleophobic coating' - they're not. The coating is only a few microns thick, but these scratches are deep enough to feel with a fingernail. They're short (<1mm) but deep.