The apartment is amazing! Really well located, right behind Palazzo Vechio, in a quiet street but close to a lot of restaurants, shops, and the city center itself.
One of the best things for us was the fact that the house was super clean. Giovanni received us very well, and he left some papers with suggestions of places to visit, restaurants, supermarkets and everything else we need to know for staying in Florence.
The only thing one has to notice is that the apartment is located in a 4th or 5th floor, and it has no elevator, so everyday you have to climb the stairs to get home. For people with reduced mobility it's an important information.
I would definitly recommend this apartment, and the hosts aswell.