We rented the place for 9 adults + 3 children/infants, coming from 4 different countries (FR, UK, Canada & the US) so it was a bit complex to organize and Donatella was very helpful and quick to respond to our many questions and requests before the stay. She even went the extra mile to purchase an additional high chair for babies as there was 1 in the apartment and we mentioned it'd be great if there were 2.
We had a few minor glitches with the WiFi and the hot plates, and both times Donatella was very quick to respond and send someone to fix everything.
The apartment is (and it is rare enough in my experiences with AirBnB) true to its descriptions and pictures. With 4 bedrooms and 4 bathrooms everyone has their own privacy, and the living spaces (living-room, kitchen) are large enough to accommodate everyone, so we managed to book a chef who came at home to cook for all of us.
There is also an extensive list of local restaurants to go to, provided by the host.
Overall, this apartment and the way it is managed are my best personal experience so far with AirBnB.
The location is also very central - alas it means it's a very crowded area all around (Florence as a city seems to be a little too "small" for the number of tourists that visit it, there are lines everywhere and you have to book most museums ahead of time if you want to get a chance to visit them), but inside the apartment it is very quiet so we got great sleep every night.
All in all, I definitely recommend the place. It's not lowly priced, but it's worth it especially with all the bad experiences one can get on AirBnB.