The only semi-useful QR code I've ever seen in real life was on one of those little reminder cards in a parking garage to help you locate which floor you parked on. I say semi-useful because the QR code took you to a webpage that told you the same exact information the card had on it, and none of my friends or I could get reception inside the garage, so we all had to wait until we were out of the garage before figuring out what was on them.
I can see the usefulness of QR codes, but I don't think I've ever seen one implemented in a non-trivial or non-gimmicky way. They're a solution to a problem no one outside of marketing had.
I once saw a QR code advertised in a Buenos Aries subway station that was just a QR code and nothing else. No graphics, logo, or ad copy around it. So having some time, I scanned it. It was just text, not a URL. (I don't remember what the text said. But it was basically just "buy slurm!"
Seemed pointless to me. This is how the public interacts with QR codes - they can't do anything that can't be done by pasting TEXT where the QR code would be.
I can see the usefulness of QR codes, but I don't think I've ever seen one implemented in a non-trivial or non-gimmicky way. They're a solution to a problem no one outside of marketing had.