Location
The apartment is located about 5 minutes walk from the main train station. Near the apartment there is also a metro station (Sondrio). However, we preferred to enjoy walking, as the centre (and the Duomo) were about 20/25 minutes walk away. For a city trip it's a great place especially if you want to go to other cities (and you need a good connection) or if you need the bus connection to the airport.
Apartment
The apartment is stylishly furnished and is equipped with everything you need, so that even a cooking evening is not a problem. You can see the landlord's love for detail. The sheets and towels provided were clean. The apartment is located in a relatively old building with a romantic courtyard and a small but working elevator. We felt comfortable staying there.
Further
The communication with the host was always quick and he was always willing to give us tips.