The flat is very modern, spacious, quiet and well located in the heart of the city and we had a very good time there. Silvia and Massimiliano welcomed us very warmly and gave us good recommendations and a map for the visit of Florence. Even if the weather was very hot, it was cold inside because of the air-conditioning.
The only problem is, that you have to pay a lot of money (in our case 63€ for 2 days) for a parking place if you come by car, because traffic isn't allowed in this area.
We would definitely come back to Massimilianos and Silvias flat !