Salvatore's flat is even more incredible than it looks in the photos. The hosts are also kind and gracious and communication was great. I can't imagine that we will have too many more opportunities to stay in a place as unique as this. We visited with our two children and this was their favorite place on our week long trip. It gives you the sense of living in Naples, if only for two nights. Staying here is like staying at your cool aunt's place, if your aunt was wealthy, slightly eccentric, and had travelled the world.
The views are superlative. Absolutely breathtaking views of the bay from all the windows that line the front of the apartment. It's very, very clean, but also cozy. You don't feel like you are staying in a hotel. We generally stayed in during the morning of our first full day just enjoying the space. The kitchen is wonderful. It's just fun to be in it. It's well stocked and even has a few essentials, like coffee! Pop down to one of the shops to buy some meats, cheeses, bread, and tomatoes and enjoy a luxurious lunch looking out at the views.
You are within easy walking distance to the National Archaeological Museum and the metro stop there. There are also restaurants and food shops nearby. The flat can be a little confusing to find so you may want to verify directions with Salvatore first.
Note that Naples is a very big, very busy city. I think it only sleeps for a few hours in the middle of the night. If you are a light sleeper used to sleeping in a darkened cave (like me), you may want to bring some earplugs. It's not music or voices, just noise from the wonderful Neapolitan streets below.