I did just last night, and I like it a lot. Nearly drove me crazy near the beginning, as I made my first steps to understanding button symbols and numbers of this game, and generally adjusting my mindset to one appropriate for solving most of the secrets.

However, I found a QR code. I found it in a temple room on a wall, I scanned it, and entered it. It did nothing. I have since not used it. If the game is to be believed, I have everything including the 3 heart pieces, but there's this one thing that bothers me, and the internet doesn't appear to have answers.

The QR codes all have alternate solutions (for those without smart phones or whatever), so it could be that you already solved the alternate puzzle.

Loved it. I go crazy for deep, hidden stuff like that. Though I do wish it led to something more. I dunno what, but something. Like, figuring out that crazy owl business and just getting another anti-cube was kind of a bummer.