I thought Leonardo's house would be somebody's apartment, like airbnbs normally are, but it is more like a little hostel: they have a sign on the door, a little reception and 5-6 rooms to rent. We had to pay 5€ per Person as a tourist tax, which also surprised us.
In spite of this, everything worked out well. The house is very quiet, the room and the 2 bathrooms where big and clean, the hosts where very kind and recommended us places to eat and what to visit in Florence :)