We stayed at Gianluca's for three nights. The location is in the Garbatella district of Rome. This is three stops on the metro from the colosseum. Gianluca's place is less than 200 metres from Garbatella metro station. It can't be considered central as such but the centre of Rome is very accessible. (Takes about 5-7mins to get to the colosseum, and from the colosseum you walk past the Roman Forum/Ruins to head to the centre of Rome).
However, for the price you're paying you can't expect to be in the centre of the Old Part of Rome.
Gianluca lives on the third floor of a block of flats. The room is located within the flat but out of the way so you don't need to interfere with the rest of the house. It's very easy to leave and enter the flat without disturbing the host.
The room itself was very nice indeed. It was clean and a good size, and actually very pleasant. The bathroom was also of a decent size, with a nice, wide shower, however there is not a full size bath tub. The bath tub is designed for someone to sit in comfortably. Again, the bathroom, like the room, was very clean and pleasant.
We had no disturbances at night, and the area is quiet so you'll likely have a nice, comfortable sleep.
Gianluca was a very friendly and helpful host. If there were any questions he was on hand to answer them. He left some croissants, tea and coffee for breakfast (already provided within the room for you to enjoy whenever). The room is equipped with a microwave, expresso machine, and a decent size fridge (containing bottled water). There is also a tv, speaker to play music, hair dryer and small fan heater. The WiFi is also fast.
Overall we had a very pleasant stay at Gianluca's, we would definitely consider going back if we were to return to Rome.