Communication with Aurora and her cousin Michelangelo was very pleasant. Good advice on how to get from the airport to the apartment. Take the Shuttle Bus (www.sitbusshuttle.com) from Fiumicino Airport at the very end of Terminal 3 (6€). The first stop is Via Creszendio 2. From there take a taxi (~7€) or the bus 70 right around the corner.
The apartment is very nice and clean. We enjoyed the terrace. Kitchen and bathroom are clean and well equiped (the shower is quite small 60x60cm).
The neighborhood and the apartment are very quiet. Bus stop is only one block away. Bus 23 takes you to Vatican city with only 4 stops or to Trastevere in about 10 minutes. All the other major attractions are easy to reach.
Would definitely come back.