We just launched this so I don't have valuable metrics yet (can publish after a month or so). However, I can tell from experience that QR codes are still "in" for most of Europe. We even had clients asking us for QR codes to be printed in brochures etc, even before we created app store app. One reason that I coded this site is to send away QR codes asap and figure out app store links later. Yes they change name of the app last minute =)