We stayed at Francesco's place during the winter of 16/17. Overall, we really enjoyed the location and thought the apartment was very nice spacious. It's located about 100 yards from Campo di Fiori, right in the heart of Rome. You could easily walk to just about any attraction you want to from it.
Francesco is a really great host. He was always easy to reach and responded very quickly to our questions. He arranged taxi for us from and to the airport, and showed us how everything works in the apartment. He also provided a crib for us - perfect for our baby.
The layout of the apartment has living room/small kitchen with a connecting hallway to the bedroom, bathroom, and a nice patio sitting area (we couldn't take advantage of patio in the winter, but it would be lovely, I'm sure, in warmer weather). Francesco did a great job renovating this apartment and made it a pretty modern living space within the hundred years old building. There was more than enough space for me, my wife, and our baby.
There were no real drawbacks, but keep in mind this is a very busy area for both locals and tourists and the price will reflect that. Also, many of the local restaurants are going to cater to the tourists, so it might take some hunting if you are looking for more "authentic" eating. Francesco is a great resource for hunting down an eatery that will appeal to you. Noise was not an issue for us, but, again, there are going to be a lot of people and cars in the area (especially when the market it going in the morning).
Overall, we really enjoyed our stay and had no complaints - nice apartment in a terrific area. We will most definitely consider this place again if we come back to Rome.