The apartment is wonderful. It is in a great location right on the Campo di Fiori piazza which is very central for walking to all the major sites. I felt perfectly safe walking to/from the property, even in the evening. The property is clean and as shown in the pictures. Check in was very smooth. Marzio arranged a taxi to pick us up at that the airport (which was great since we were a bit jetlagged and it meant we didn't have to think about anything!) and his colleague Jasmine met us as soon as the taxi pulled up to the apartment. She was helpful and friendly, showed us all the features of the apartment and got us set up on the wifi.
One thing to keep in mind is that Campo di Fiori is a very busy square, and with the windows open the noise from the square is quite loud. It created a great ambiance for the afternoon/ evening while relaxing in the room, but was too loud to leave the windows open for sleeping. With the windows closed, it blocked out all the noise and was perfectly quiet for sleeping.
Overall I would highly recommend Marzio's property and would stay here again if we ever return to Rome.