It is also similar to a debit card from what I understand, and is good at all things Disney unlike the certs which were only good for specific parks from what I understand. Even good for Disney Store Purchases and catalog purchases.
You also do not have to order them ahead of time, you can go down to a customer relations station (same place to activate your AP) and they will issue it to you there.
and the Disney Visa rep said they had been swampped with orders since the mailing went out. Went ahead and ordered mine with the required 20 and will have the balance of my points transfered over right before we leave next month.