I had a pleasant stay at Alessandro's listing. Here are some helpful tips for potential guests:
(1) Location: it is about 5 min walk from Piazza del Duomo but still quite at the night.
(2) Apartment: The listing is on the 3rd floor with many steps. Rooms are bigger in the real life and everything was great.
(3) Amenities: Wi-fi is weak but bearable. The heater works well but the apartment is so huge that it still felt a bit chilly in the listing. I would love to come back only if it's not in winter because even in March it was a bit cold.
Thanks, Alessandro & Tomaso for all the help!