Polarr is using them as the way you share/install filters in their apps. Snapchat is also using a variation of it for adding people to your friends list.
I also did use it to scan a snapchat contact in once as well. That was one of the few times I used the QR code and it was also the only time I (barely) used Snapchat. It was also very frustrating, but if I did it all the time it wouldn't have been a big deal and therein lies the problem for trying to use the QR code on a widespread basis. Even when you know how it works, there is no universal understanding of what data the codes plug into. It could be any of the following: a website address, a Snapchat contact, a product, a Polarr filter, an app code, and so forth.
They're superior to bar codes because they're more compact, but ironically because they're so versatile, it's hard to know exactly what it's for and so that results in frustration. Bar codes can be used for a lot more than just retail products, but they're so tightly associated with products that we know what's likely to happen when we scan a barcode. You get a price or you get additional product info.