The apartment is located in a calm street. We stayed over a weekend and were not disturbed by any noise at night. It is within walking distance of Bairro Alto, where you can find lots of bars and restaurants open until late at night. The apartment is comfortable with the necessary amenities and the check-in by Maria Ines' colleague, Laura, was very friendly - lots of recommendations of how to get around the city and where to go visit. FYI, there's a 10€ fee for late check-ins (we arrived at around 23:45).
One of my friends left behind her apartment keys, and Maria Ines took the trouble to send them back to Paris by mail (thank you very much!).