I stayed with two friends in Marzia's apartment, which is in a great location (Campo de 'Fiori) as long as you are not a light sleeper. I can tolerate a moderate amount of background noise, and I was able to fall asleep easily, but you are staying above many restaurants and have an open-air market right at your doorstep. Her husband, Fabio, was waiting for us in the plaza (even though we arrived to the apartment 45 minutes late due to our flight) to give us the key and show us the apartment. He also helped us find a parking space (which by the way is not easy! The best deal was the parking garage by the Vatican museum, 20 euros/day). The only unexpected part of the process was that you need to pay extra for use of the kitchen, which was not clear to me when we made our reservation (and we decided against paying the 50 extra euros for the kitchen). Beds, shower, and linens were comfortable and clean.