I have been using AirBnB for years and this is probably one of the most cosy and charming apartment I have had a chance to stay at.
Not only is it perfectly located (Duomo is at walking distance), but it is in an ancient building with unusual volumes, windows, rooftops. You are really living the Florence experience. As a bonus, the apartment is colorful and the artwork hung on the walls, the atmosphere, gives this little additional feeling you would never find in a standard (boring) hotel room. Convenient supermarket, café, restaurants nearby. I would definitely stay here again!