Marina's apartment is in a very good location if you want to be close to the Duomo and its surroundings. A metro and tram stops are very close by too.
The apartment is well equipped including a washing machine, the heating is great and the water pressure is perfect.
For us it wasn't a bother to climb a flight of stairs to reach the apartment.
The apartment is in a gallery of shops and they have gates at both entrances which close in the evening - for us it was a plus as it made us feel more safe.
I would recommend it if you are visiting Milan.