While QR codes should really live up to their name, in reality there is nothing "Quick" about using them. You unfortunately have to download an app, open it, hold the phone over the code and wait for it to process. This takes far too long to hold anybody's attention, and is why traditional media such as posters are far more effective marketing tactics and why you really don't see many QR codes. Going back to the opening paragraph, this technology was created for quickly scanning the content in boxes, we have since tried to adapt it into a marketing tactic. Another example of a similar misused technology being seen a lot this holiday season are TV commercials using Shazam. In the time you are warned to take out your phone and start shazam'ing a commercial for more info, you are left with about 3 seconds(if that) for the app to actually process the music and take you to the micro site...in which it usually doesn't because it needs more time to process the music.
There are new technologies that are out or on the verge of being released that aim to eliminate the lengthy process of utilizing QR codes and still yield similar results. One of these is called GPS based push notifications, which could be used to serve deals or promotions by simply walking near a flagged area. Technology like this may put QR codes in their grave as the automation completely eliminates the innate flaws of QR codes and similar technologies.
A great example of the move away from QR codes can be seen from some large companies this holiday season. Specifically, Starbucks and Target who in years past dabbed in QR codes, but this year have opted to use more interactive technologies such as Augmented Reality. Augmented Reality, if you don't know is a live, direct or indirect, view of a physical, real-world environment whose elements are augmented by computer-generated sensory input such as sound, video, graphics or GPS data.
I'm a firm believer that QR codes are on the way out in 2012 from the emergence of more automated and interactive technologies...or possibly the mayan calendar.