I contacted the host by phone before I booked. He gave me lots of useful information and helped to arrange late checkout.
The apartment is located on the corner of Dorrego Plaza that has a flea market on Sunday and tango afterwards. During the week the plaza has some nice outdoor restaurants.
It's on the first floor which is nice for hauling luggage. There are no windows but has a large indoor courtyard that brings tons of light into the apartment. All the rooms open into other rooms so there's not much privacy but it wasn't an issue for us.