We had a wonderful stay at Gaby's house - three adults and three kids (10, 8, 4). The house is as shown in the photos. There are three bedrooms, and then there is a kind of mezzanine floor with two flat couch-benches that can be moved together to make a double bed. The house was very well designed and contained everything we needed (kitchen supplies, towels, sheets, etc.) The light inside is phenomenal and the patio was truly lovely - it was a perfect place to unwind during our breaks during the day, and in the mornings and evenings. It really was an oasis in Mexico City.
The location is in a very quiet area, yet also convenient - about 15-20 minutes from downtown Coyoacán, 10 minutes from Frida's house, and just a few minutes from Viveros park. (These are walking times with kids -- without kids I imagine they'd be shorter.) There is a supermarket about 4 blocks away as well as a pharmacy. Gaby is lovely and both she and her sister were very responsive to our questions. And it gave us peace of mind to know that Gaby is a pediatrician (and herself has young kids).
During our stay there we went to Tlalpan, the Museo de Antropología, San Angel (our kids loved the restaurant L'Encanto de Lola), and of course to Frida's house, the Coyoacán plaza, and Viveros. (Note that there is actually an entrance to Viveros on Calle Madrid, closer than the way Google Maps tells you to get into the park.) We didn't walk outside much at night, but the one time we did we felt totally safe. We highly recommend the house and would return there again!