We stayed for 3 nights and 3 days and really enjoyed my stay in the apartment.
Best part of the apartment is that it is located in heart of the city. One can get city pass and take tram no 2 to reach Metro station at "piazza del popolo". Rest of the sight are at walking distance as well.
I like Martina, she was very good host and helped us with lot of information (specially place to get best pizza in Rome).