We had a great stay at Campo de' Fiori in september 2016.
The apartment is ideally situated for all the sights in central Rome. The market just outside the window is very lively all day but the windows are almost soundproof.
Our hostess Bettina was most helpful during the whole stay. The only small con would be cleanliness, a bit dusty and visible spiderwebs in sunlight. But overall we would deifinitely recommend anyone to live here!