Only works with Guinness.
Yes, except for an obvious flaw, which I am going to state in as profane a way as possible so as to give it appropriate emphasis:
WHO THE FUCK GIVES A SHIT ABOUT A QR CODE ON A FUCKING GLASS OF BEER?
I’m going to assume this is some student design project or some other type of demo work which will forever remain blessedly unrealized, because I believe the Guinness people are intelligent enough to realize that if they’re going to supply bars with promotional glassware, they might as well JUST USE THE GUINNESS LOGO, which is one of the most well-recognized brand names/logos in the WORLD, and which does not require some idiotic smartphone app to look up and translate into the Guinness URL WHICH ANYONE COULD HAVE DEDUCED ALREADY.
If some marketeer at Guinness really wants to put the URL on the glassware, then just put the URL on the glassware. UNDER THE LOGO.
This is the problem with QR codes. They translate to a URL. But their information density is actually LOWER than just printing the URL as text - they take up more space on a page/glass/screen/wall than the URL-as-text would - and they are opaque; you can tell where an URL goes just by reading it, but you can’t tell where a QR code goes until you scan it (hope it doesn’t lead somewhere you didn’t want to go!) It adds a needless extra step to a process that was already simple and transparent. It’s a fix that makes things worse.
The only reason QR codes are hot right now is because of the number of people superficially fascinated with smartphones who 1) need amusing things for it to do so they can show them off to other people and justify the price they paid for their status gadget and/or 2) are too lazy, or frustrated with the difficulty of typing input on those little things, to just type in a URL.
But as smartphones become so ubiquitous that they just become “phones,” the use cases will divide into two groups of people: the power-users, for whom the other capabilities of the phone are genuinely essential to their everyday life, and who have learned to use their phones efficiently and intelligently … who, in general, will be smart enough to realize the inherent problems in QR codes and not bother with them, especially as input methods for text improve; and the phone-focused users, for whom the extra features in smart phones are occasional and ancillary, and who will quickly lose interest in gimmickry like QR codes once their phone becomes just a phone to them and they stop wanting to show it off every five minutes.
QR codes are a fad, and one with a very short shelf-life. You read it here first.
EDIT: Of course there are all sorts of nuances and wrinkles to this, and a very interesting conversation on Twitter has ensued which unfortunately I now have neither the energy or the patience to duplicate here. I will point out one thing, though: I don’t think QR codes are useless, and I never said they were. There are a whole lot of applications where they are much better than bar codes. I just am tired of seeing them plastered on every single wall and advertisement in the universe, and I think - I hope! - that soon the rest of the world will get tired of them in that aspect as well.