1.) While the QR code is relatively compact, it still requires a bit of real estate on the printed material. A 2" x 2" square could be used for other things, say a picture, graphic image and web link. Is it any eye-catcher? Yes. But how often does it really get scanned? Read on...
2.) To read the QR code, you'll need a specialized reader or a smartphone enabled with a QR reader. Think about what you need to do: pull out phone, start up the QR app, snap a picture and then let it do it's thing. We're talking 15 - 30 seconds, give or take. And the result? Most likely a special web landing page with an offer or more content. Wouldn't a shortened weblink work as well? And given that only 35% of adults own a smartphone and only 3% of that group is using a QR code reader more than weekly, we're talking about a very narrow and small target group.
3.) And finally one of the most interesting aspects of a QR code is also one of the most unsettling: the mystery of the QR code! Where will scanning this QR code lead me to? What special online offer can I get? The danger of somebody potentially embedding a malicious QR code on the re-direct seems very possible. And do you just click on any weblinks that you see online? Not a good idea and certainly not a safe one. Practice safe-computing, people!
So in the end, while the QR code fad may be around a bit longer, I can't imagine it will be much longer. They were initially developed for high-speed, automated scanning in the auto industry. Given its current deployment and use by a slow-speed, non-automated human being, I'd say that QR codes are misplaced and ineffective in most printed assets. Just scratch one up for tech-geekiness gone wild in the marketing space.