We had a good stay at Antico Palazzo Salsa. Christian was very helpful, quickly replying to our queries and helping us sort out the chaotic traffic of Napoli, even organising parking on the same building. He also gave us lots of tips about what to do and where to go.
The apartment is spacious as described and well equipped. The area is not the nicest of old Napoli but is well served with cafes, markets and grocery stores, and two buses take you quickly to the historic city center (otherwise it is a 30 min walk).