We were 2 persons (dad and daughter, using the 2 double folding beds, 4 people could perfectly sleep there) and enjoyed 4 nights in Stefania's apartment. The whole experience has been very positive! She answered all my requests/doubts (E-mail, Whatsapp) in advance and she replied in a fast, friendly and helpful manner. Another positive thing was her flexibility, she did her best to adapt to our arrival/departure time.
The flat is cozy, very clean and almost new (all the electrical appliance and kitchen/bathroom/bedroom stuff is brand new, in excellent conditions!). It is a ground floor aparment with interior views, practical, it is not big but I can promise that it will perfectly meet all your needs!
The area has affordable bars/restaurants/supermarkets and the apartment is well connected to few buses and metro stations.
So, to sum up, I would say that Stefania's apartment is a good choice, you would not regret, your stay will be a very good value for money! ;-)