We stayed 4 nights in Buenos Aires. The room is indeed right in the centre of the city and we felt like home in Maria Lucria's apartment. The Plaza de Mayo is at a 5min walking distance, making it very easy to use the subway (Subte) and buses.
The neighbourhood is very pleasant and very calm on the weekends, with a lovely market on Sundays.
Maria Lucrecia helped us a lot, giving us very useful advice on where to go and how to go there (including for our way back to the airport). It was great to talk about Buenos Aires and Argentina with her. We discovered places we wouldn't have without her tips.
We highly recommend this place for anyone looking for a true "porteño" experience.