I saw a poor barista trying dozens of times to make the reader accept a card the other day (Square + iPad, not sure if they were using this exact set up). It got quite violent. The scanner does really seem to be far too flimsy to be the primary payment mechanism in a busy business.
True. I used Square's NFC-like Card Case app at the same coffee shop and the experience was much better. It was a little disconcerting to complete a transaction without an physically action like a swipe or button press though.
