My wife, sister, brother-in-law and I stayed at Sergio's for five days late in May.
First the pros: The location was ideal, just a three minute walk to Piazza Navona and for us, within walking distance of pretty much all the main sites. The apartment was spacious but old and musty. One might expect old and musty considering the age of many of the buildings but our subsequent stays in Florence and Venice proved that it doesn't have to be this way.
The cons: Washer and stove did not work and there was no hot water when we arrived. Despite trying to contact the host several times through the AirBnB site and by text and phone call, the host could not be reached. We had to contact AirBnB support to rectify the situation and to their credit they were terrific ... sympathetic, fast and got results but it was 10:30 pm on day 2 when our host, Sergio finally fixed the hot water issue. He promised to return the next day at 11:00 am to fix the stove and to bring more face cloths (there was only one) and more toilet tissue (there were only 2 rolls for four people for five days)! Needless to say Sergio was a no-show the next morning and again unreachable. We gave up on him, bought our own supplies and dined out the entire time we were in Rome.
An earlier review from March had mentioned the washer did not work but we assumed the host would have fixed it by late May as it was still listed as an amenity. It's our impression that Sergio didn't seem too concerned about providing a positive experience for us. Book this apartment at your own risk. Perhaps you will have better luck.