My girlfriend and I stayed at Marco's place for 4 nights, and we had a great experience.
Communication between Marco was nice and fast, and we were greeted by Marco and his wife at the apartment upon our arrival.
The apartment was nice and very clean and had all facilities you would need.
Although it is not located in the city centre, you can take a bus nearby and be near all the big sights in 15 minutes.
The neighbourhood is quiet apart from the nearby train station.
All in all it was a nice and smooth experience and we had a great trip to Rome!