There is no real gain in convenience compared to a Starbucks Card or cash, and you still have a paper receipt involved in the transaction. I'm having a hard time seeing how this is a step forward.
The ability to reload money on it is an advantage as well. Not sure if there is anything advantage to a starbucks card in general; discounts, give aways, other than the wireless, but I like the app approach over the plastic in my wallet.