Visited May 2013 and the all-you-can-eat buffet is available all day now, 15 soles per person including 4 vegan soupy dishes, noodles/rice, fresh vegetable salad and mineral water. It was a real treat to have unlimited water included in this part of the world! It was also pleasant to sit at one of several tables on individual balconies overlooking El Sol street.
For being right off Plaza de Armas in the most touristy area of Cusco, I thought the prices were reasonable. You can order a la carte items as well -- the full menu is on their website, we got chapati bread, 2 pieces for 5 soles extra.
The environment was calm and the service was pleasant. Recommended if you can eat a lot to make it a good value!Pros: Healthy, Free water!, Tranquil
Cons: Dishes a bit lacking in texture