Unfortunately, our enjoyment of this lovely apartment was spoilt by the check-in process. Upon arrival we were presented with a tenancy agreement to complete and sign. We refused, pointing out that we had already paid for the apartment and the agreement had been concluded through Airbnb. Our hosts did not seem to understand why we would have a problem with signing a contractual agreement relating to a service for which we had already paid. It became clear that we would not be able to stay in the apartment if we did not complete and sign a contract. We were under significant duress at the time, being already tired and stressed, and we were reluctant to gather up our bags and go find a hotel - so eventually I gave in and signed. Subsequent advice from Airbnb suggests that this is "standard procedure" in many cases in Italy, suggesting that Airbnb is aware of, and condones, this dubious practice.
I should note that our hosts were at all times sympathetic to our concerns and subsequently gave us a bottle of wine to apologise for the distress we experienced. They were also very responsive and helpful with other matters during our stay.
For your own peace of mind, I suggest any prospective guests request a copy of the tenancy agreement from Patrizia prior to booking. I note that Patrizia has now included a reference in the listing to the requirement for "an agreement for the touristic rental of the property". As is customary practice, any such contract should be signed by both parties before payment for the services provided under the contract is made.
The apartment itself is cosy and comfortable, with lovely views of the Duomo and Giotto's tower. It is perfectly located to see the main sights of Florence and close to many restaurants and shops. Because of our heavy bags, we struggled with the narrow staircase, but this was very much a self-inflicted problem! We rely heavily on connected devices in our travels and chose all our Airbnb hosts in Europe partly on the basis of the availability of WiFi - unfortunately, in this case, the WiFi connection was frustratingly slow and the signal did not reach most parts of the apartment. Because of low water pressure in the building, you may find that water for taps, toilet and shower is frequently interrupted by people using water in a lower floor apartment. Make sure you allow extra time to take a shower if you are on a schedule!