"At worst, the service simply did not work. On average, however, the user experience was buggy and awkward, with Starbucks employees seemingly more confused about how Square works than their own customers."
I used Square once or twice when it debuted, then went back to the Starbucks iPhone app -- and stuck with it.
Do you use Square, customers? Baristas: how many customers use it and have you been properly trained to handle Square transactions? Let us know!