We had a perfect 1-week stay in this apartment. It is in a calm street in centro storico, in a courtyard where I think mostly locals live so you can feel like a real Neapolitan! Very quiet in the mornings and the bed is so comfortable. There is everything that you need even a waching machine. Spaccanapoli is only 1-2 minutes walk. We rarely used public transportation (maybe 3 times) because the port and the train stations are also in walking distance (20 minutes approx.)
Our host was very kind, flexible, responded quickly. Not to mention that the price is unbeatable!
I would stay here again.