I have stayed with Paul and Mary for a month - and have only positive experiences. Paul and mary are both super nice, honest, helpful and welcoming people. Paul showed me all the nececities around the neighbourhood and introduced me to BA in a super way.
There place is having a super locacion, near the best transporttation hub, even though the place itself is quiet and tranquil. It is located in San Telmo, one of the must sees parts of Buenos Aires in the Lonely Planet travel guide.