Very popular with gringos-as volunteers we went there whenever we were in Cusco. The atmosphere is laid back-it is good for chilling out, chatting and reading/catching up on journal entries.
Although the food is snack food, it is filling. Especially good are the soups, or the potato skins. The baguettes are good to take away for a picnic (they also do special picnic food). For drinks, the iced-chocolate is good, or a special smoothie (great for hangovers!). Alcoholic drinks are quite pricey.
Average cost of a meal is $3. There is a good net cafe a few doors away.