It' a cozy apartment in the center of the city, very close to Plaza de Mayo. Very easy to get there from the airport using Tienda Leon bus service. It takes just couple minutes to walk from the bus station to the apartment.
The check-in and out are very flexible. We arrived in BA in the morning and could check in by 11.00 and had a late flight back home so we could check out very late afternoon.
Nilda was very responsive and helpful to find good restaurants and places to see. She even provided a "SUBE card" which you can use for public transportation. This card works like a debit card and you can reload it when you use up your credit.
In one word: "Todo Bien"
.