We stayed at Marisa's place for four nights and we were very pleased. Marisa greeted us when we arrived, showed us around the place and provided suggestions (along with detailed maps) of places to see. She had several ways to reach her if we had any issues during our stay - which we did not.
Marisa's place is clean and comfortable. Has a nice balcony overlooking the avenue and an elevator in the building.
The place is centrally located to many of the sites either by taxi, bus or subte.
Would recommend Marisa's place when in Buenos Aires.