Ask HN: Product idea involving QR codes, any advice ?

Hi everyone, I'd like to know if anyone has worked on QR Codes before. I have a product idea that ideally I'd like to turn into a startup and it involves QR Codes read by mobile phones. I'd like to know if anyone has hit a wall with this technology or any issue I should be aware of. On my HTC Desire, reading QR Codes works perfectly but I'm not sure the experience is as smooth on other devices ( I target Android/Blackberry/iPhones mainly ). I'm also not sure about people's perception of this technology. Any experience or advice would be greatly appreciated.