While copying magstripes is already easy, no merchant will accept a stock magstripe card for a credit transaction, because it's clearly fraudulent.

If merchants will accept coin, it creates trust for this devices, and lookalikes. I think it would be much easier to create Coins, or Coin clones with stolen credit card data. This is rather concerning.

On another note, I really want one of these to tear apart and mess with. The hardware is pretty slick.