One of my biggest gripes about QR codes used as an advertising vehicle has little to do with their effectiveness (although I do have doubts about how effective they are in the long term). One of my biggest gripes has to do with the lack of creativity that goes into the global experience that surrounds them. Especially the most important portion which happens after the scan takes place. That overall lack of creative design is what leads to most call to action failures when it comes to QR codes, or NFC based campaigns as well.
A great example of where the post scan action is extremely creative, and effective is CP+B‘s “Couple Up to Buckle Up” campaign for Scandinavian Airlines. The campaign uses two unique QR codes across every touch point, from email to Facebook, print, to direct mail etc. that leverages how couples commonly book trips. The campaign works like this, couples each scan a unique QR code which displays half of a video offer. In order to get the offer to work, both smartphones have to be connected to get the entire promotion. Simple yet effective game play that helps extend the offer and build the brand in a fun and memorable way.