I've spent two nights at Magda's place and I had a pleasant stay. The flat is big and beautiful, filled with old and charming furnitures. I rent the smallest guest room that is indeed very small and the wifi didn't work very well inside the room but it was all right for a short stay. This bedroom has a private bathroom ensuited so I was comfortable there. The flat is very well located, to me you can't beat this location as San Telmo is my favorite neighbourhood.
As for Magda, she did her best to make me feel at home. She's is a very interesting woman who loves theater, music and arts in general. She offered me to share breakfast with her one morning and was kind enough to tell me interesting stories about her life and how it was to be an art student in Argentina during the military dictatorship.
If you like authentic and charming places and persons, you will fell very goog there. I recommand it!