You may think that no one uses QR codes, and for many applications you would be correct. Consumer adoption of QR codes in advertisements and on social media has never taken off, for many of the same reasons the CueCat never gained widespread usage. While scanning a QR code with one's smartphone is still a lot easier than taking a magazine or other printed material to a computer and scanning it with a weird-looking accessory, it still requires a user to get the phone out, load the QR app, and scan, in many cases just to get to a URL printed on the same page. Most advertisers would be better off using a short, memorable URL instead of requiring a reader to try to scan QR.
However, QR codes are taking off in the field of mobile ticketing. They offer many advantages over the traditional bar coded tickets, in that a QR code can contain much more information in the same amount of space, can be read in different directions (reducing alignment confusion), and are more difficult to forge. QR codes are easier to read off of a mobile device screen as well, which makes them an enabling innovation for mobile ticketing.
Although the ticketing startup Mogotix seems to have gone the way of the dodo (no new tweets in 2 years, website is completely gone), many traditional ticketing companies have gotten into mobile QR ticketing in a big way. The next time you attend a ticketed event, you may well be able to leave the paper tickets at home and just scan your phone for entry. This innovation saves trees, time, and aggravation for everyone!