For me the card makes sense. I pop into Starbucks in the morning probably four times a week. Occasionally in the afternoon too.
There are a few minor things I don't like about the card. The discount doesn't apply to buying the NY Times (the main reason I go to Starbucks). Second, you can pay with the card if it's set up to do so. Or, you can let them swipe the card and pay another way. That means that you give them the card, they swipe it, and then ask how you want to pay. Somehow it seems like an annoying extra step. Last, and this is just my personal thing, the card is black, and so is my wallet. It's really hard to find.
Yes, I need to get a life.