Great place to stay in, very close to the center of San Telmo, which is the lovely old part of Buenos Aires.
I had an amazing time there. The flat is spacious, airy and full of light with a little balcony.
It is around 10 minutes walk from plaza Dorrego, a really nice square to have a drink.
It is close to san juan metro so you can reach any part of the center quite easily.
Guillermo is an extremely friendly and helpful person. He lives in NY but has friends that will help you to settle in. You will feel home!! I will come back if I can