If you like good coffee, I would not recomend the Starbucks kiosk at Shades of Green. The workers are not Starbucks employees and they make some of the worst coffee I have ever had.
The Starbucks in the Premium Outlet is good and is located in the Food Court section.
You can get excellent espressos, lattes, cappucinos, etc. at the coffee carts in the Italy section of Epcot.