Hosts: Berenice and Horacio were very friendly and I was able to get by without having taken any classes in Spanish. The free breakfast is more than just food, since you have a unique opportunity to talk with them and learn things about Mexico City you'd never find in guidebooks. Of course if you'd rather be left alone or sleep in, they'll respect your privacy: the guest rooms are located across the hallway near the entrance, and they'll simply place the food over in the guest area.
Cleanliness: The breakfast is always artfully presented, and Berenice will ask if you have any dietary restrictions. Before coming in I was a little worried about food or waterborne illness, but everything I saw here put my mind at ease. I had a chance to help Horacio prepare breakfast and noticed that he would wash all utensils twice before using them. He would sometimes prepare food using vegetables from the rooftop garden (which you can visit, and even eat dinner in!), which were washed in iodine-sterilized water. Drinking water is also provided for guests - this is safe bottled water.
Safety: I felt safe in this neighborhood. Returning at night, I would regularly see families taking a stroll or getting dinner. There were also police patrolling the area.
Location: The location also makes it very easy to access the city center. Unlike most listings, your primary way in will actually not be through the subway (although there are subway stations within walking distance) but rather bus line 7. This is a considerable upgrade over the subway: the buses are fully air-conditioned and double-decker, so you can get a full view of several of the city's main sights as it goes up and down the Paseo de la Reforma. Street food in the neighborhood was also excellent, and in my opinion even better than in the city center because it was catered toward locals.
I'd definitely stay here again, and recommend friends and family to do the same!