We absolutely had a great time at Alessandro's place. The house is wonderful and very welcoming.
The room is really big and, as you can see on the photos, it is a former chapel and so you sleep right just under a beautiful fresco of an Annunciation !
We also really appreciated to have lunch on the terrasse under the shadows of the wistaria.
Alessandro is a perfect host as he provided us several maps and travel guides of Florence (it was lovely let on a table in the room), plus his excellent advises about the city and its surroundings.
The house is situated on a main axis, not so far from the center (15 min by bus), and there's a bus stop right next to the door. De facto it was a bit noisy in the room because of the traffic next to the window. We would recommend to have some earplugs if you're sensible to the noise.
So, to sum it up, we would definitely recommend this place both for itself and the hosts and we would be happy to come back again.