Location, location, location - San Telmo is the perfect home base to see what beautiful BA has to offer. Taxis are cheap & Ubers even cheaper, so getting up to Palermo & Recoleto, or over to La Boca or Puerto Madero is a snap.
The apartment is just off Plaza Dorrego, which in addition to its famous Sunday flea market, hosts tables & tango from adjacent restaurants nearly every night.
It's a stylish flat, nicely equipped, with a great super (Jose), who is always available to help in any way.
One caveat, however. Privacy between the downstairs & loft bedrooms is scant, as there are no doors to close upstairs. But if you are traveling as a one couple or with children, this is the place for you.