We spent almost a whole week in David & Malu's apartment and it was great! The house is located close to Mergellina Station, so you can easily reach the city centre or Pozzuoli (where you can take ferries to Ischia and Procida). Carrefour Express is 2 min away and opens til 21:30.
The house is really beautiful: amazing decoration full of books, cds, and plants. The terrace is great to enjoy a glass of wine after an exhausting day visiting this crazy city.
We only met David. He was very kind and helpful to us. We could reach him on the phone every time we needed, he gave us lots of information and tips about the city and surroundings (Ercolano, Pompei, Capri, ischia...)
I would definitely recommend David & Malu's apartment for a nice stay in Naples.