While it may not be a big deal to all people, apps such as this provide a convenience to many of us that impact which device we carry and which coffee store we visit. This new Window 10 Mobile app supports registering and using your Starbucks cards, reloading them with value, digital tipping of your barista, checking your reward status, and locating stores. The only feature I don't see at first glance is the ability to place and pay for your order in advance of your visit.
You can download and install the official Starbucks app from the Windows Store now. The app is free, but you will need a Starbucks card to pay for coffee at the stores.