This was our first time to Europe/Italy and our first time using Airbnb, and it was a great experience.
The flat is in the perfect location, about a block away from the Colosseum. Many other attractions are within walking distance, but the metro stop is also only a block away in case you need it (we bought a 1-week metro pass for about 24 euro, which was convenient). The metro will also take you to Termini station in case you want to visit any other cities during your trip (we took the train for an overnight to Venice, for example). There are plenty of restaurants and shops in the area, including a great breakfast place right outside the flat (these places are closed at night, so it's quiet during the night and bustling during the day). There's a university right around the corner, so there's lots of college students nearby during the day. The building housing the flat is a beautiful old building, but the flat is modernized and comfortably furnished. There is an elevator which is great when checking in/out with your luggage. Our only complaint would be regarding the hot water system, it's very temperamental, but you'll get the hang of it (*you may also have to turn the system on in the closet, FYI).
Giovanni was a great host. We booked a few months in advance and he kept in contact with us. He arranged a private car service for us, both ways from the airport (at about the same price as a taxi) - the car service was reliable and punctual. The internet router broke during our visit and he quickly replaced it for us. We were very satisfied with how Giovanni accurately advertised the flat, and with our interactions with him. We didn't get to meet Giovanni in person, but his friend Flavia met us upon our arrival to give us the key - she was delightful and gave us some helpful information about the area.
I would highly recommend this flat and Giovanni as a host.