I've used Airbnb a fair few times now, but Stefano's apartment is hands down the best Airbnb I've ever stayed in. The view from the balcony makes it worth every penny, the bed is very comfortable, the kitchen is well stocked and everything is spotless. The only drawback was an unpleasant smell coming from the bathroom, I couldn't work out what was causing it but I've since mentioned it to Stefano so hopefully it will be fixed shortly!
Also it is a top floor apartment and there are five flights of stairs to climb with no lift. We're relatively fit and it had us out of breath, especially when we arrived with our luggage. This is typical in older buildings but anyone staying here should be aware that it might not be suitable if you need a lift.
We didn't meet Stefano, but we met his associate (I think her name was Amy) who was very friendly, and helped us find an ATM so we could pay the city tax which we had forgotten to bring cash for!
We took ear plugs because we are both light sleepers and I'm very glad we did because the piazza below the apartment is very lively into the early hours of the morning. This isn't necessarily a bad thing, we found it lovely listening to the music and the people from the balcony at night but we would definitely recommend having ear plugs handy if you plan on going to sleep before 1 or 2am.
The apartment is within walking distance of all the major attractions in Florence. Only 5 minutes from the Palazzo Pitti and the Boboli gardens, 5/10 minutes from the Ponte Vecchio, 10/15 minutes from the Uffizi gallery and about 15 minutes from the Duomo.
Overall Stefano's apartment is beautiful and I highly recommend it for couples or friends!