It's good that the article did bring up potential security risks, especially with the credit cards. Ok, the bands don't have the credit card info on them, and the guest must use a PIN code to fully utilize that, so you do have 2-factor authentication for that part. But you do have to wonder if the bands can be cloned. This would allow someone to get into hotel rooms or use them to get into the parks, etc.
Here is a Disney Blog posting on it.
|Backside of MagicBand|
|Payment stations that use the MagicBand and enter PIN.|