I handed out about 200 cards that weekend and there were about 3 people that scanned the QR code and bought it on the spot (right in front of me... now THAT was cool).

Keep in mind that this is 95% women in this industry, so I didn't expect them to be as "tech savvy" than if I was at a computer conference or something.

I believe that the personal touch of saying, "I built this for someone like you" has a HUGE impact on how people feel about your brand and your app.