The apartment is really nice, clean, well equipped (there are towels, umbrellas, basic products to cook, plug adaptator, precious information on ferries and trains, etc.), situated near via Toledo and near the historical centre. It is not big, but there is definitely room enough for 2 and it is well organized so you don't feel like missing space.
Its main asset is the splendid terrace with its amazing view. It is a pleasure to have breakfast there or a glass of wine at sunset. The place is quiet. It was possible to sleep with the window open to keep a cool temperature.
Marina is a nice host. It's really easy to get in touch with her and to organize check in/out.
I would thus recommand you this place for a stay in Naples!