It sells coffee and iced tea. It's drinkable. The lemon bars are good.
Really, the big advantage Espresso Royale has is convenience; it's two blocks away from the quad, and the prices aren't horrible. But I'm thoroughly unimpressed by the overall quality, and the place looks like a grad student's apartment: a strange mishmash of chairs that sort of fit together. At least it's not another Starbucks?