Alessandro is the ideal host : very helpful (he took our luggage at the airport so that we can visit the city to wait for the flat to be ready). His advice for the restaurants (typical italian restaurants with no tourist) around the flat was also very appreciated ! The flat is located in Testaccio which is very close to all nicest monuments of Rome. Also, they are many bus lines next to the flat in case you do not want to walk anymore.
I would definitely recommand this flat which is perfect and well furnished for 2 people.