Andrea is an excellent host! She was very quick to respond to all of my questions both before and during my two-week vacation here. She even helped me find transportation to and from the airports.
This apartment is in a great location for exploring San Telmo, going to the Sunday Féria, several tango show locations as well as walking through City Center and to Recoleta and Puerto Madero. Palermo you’ll probably want to taxi or take public transport. Same for La Boca since certain sections of the latter are sketchy.
I felt comfortable walking around in the neighborhood in the early evening. Not sure that I would feel comfortable after, say 22:00 unless with a man. That particular block is a little rundown.
The apartment itself is very comfortable. My only complaint is, as others have noted, the water heater is very small. Very difficult for two people to take a warm shower in the morning or evening, even with allowing time for the water to reheat. Even for one woman, the hot water runs out fairly quickly.
I would definitely stay here again. However, in hindsight, I would have split my visit and spent part of it in the Palermo neighborhood. The nightlife there seems much more young and vibrant.