I received my Coin about 2 months ago. I was excited to test it out after preordering almost 2 years in advance. The concept of having all my cards on one central card was a great idea. But having it not work at some locations was rather embarrassing and frustrating. I have decided the Coin was a fail and I will not carry it anymore. But, Coin, keep innovating. You tried.
It sounds like just another startup hardware offering with a spotty launch. But I've always been confused about the perceived "embarrassment" of a card not working at the point of a transaction. This seems to be a common marketing trope in payments, but I don't know what it comes from. It's a piece of technology, and tech often doesn't work quite right. Sometimes my phone restarts itself. What's the big deal?
Another common cause of credit-card-swipes not working is card declines. It's fairly obvious to the user and cashier, but potentially embarrassing if the people in line behind you assume you've maxed out your credit card/drained your debit card.