The place is located half way along "Gringo Alley," so called for the cheap restaurants, shops and hotels located here. We thought half the fun was just trying to make our way past the many hawkers trying to entice us in to their restaurants on the way!
El Cuarte is one of the few restaurants that doesn't have hordes of people trying to drag you in. I think they have a good reputation anyway and don't need to. All the restaurants in the alley have one or two token Mexican dishes on their menu, but this was the only "dedicated" Mexican restaurant. It was also a nice change from the standard dishes on most restaurant menus here.
When you do finally arrive what you will find is a cosy restaurant made up of a couple of different rooms and, I believe, an upstairs section, but this was not open when we were there.
The menu has all the standard Mexican dishes, along with various set menus, for reasonable prices. For example, with a set menu would be included a small chip and dip, a soup, your choice of enchilada or similar, and a dessert, for between 10-15 soles. I would not recommend ordering a set menu for each person as we made that mistake and it was just far too much food. You would be better ordering one set menu with an extra main for two to share. Since it's at such a high altitude, appetites are lower and if you eat all that is served with the set menus you, feel like rolling back to your hotel and lying down for a few hours before being able to sleep.
They also have Pisco Sours, Sangria, and wine by the Jarra or glass. If you pick up one of their small flyers it entitles you to A Pisco Sour gratis. Yummy.