Stay at Marco's place was very nice. Marco is friendly and accommodating. The place is well accessible by walking (it is up the hill though) or by funicular. There is a shop not far from there.
The place itself is in the lowest floor of the building. There is not much of a view from there. In the vicinity there are not many restaurants, so it is better for people who want to explore different areas of Napoli and not spend the whole day at the flat or just nearby.
I can recommend this place.