Massimo's appartment is great, exactly like in the pictures. Everything is new and clean. It is equipped with anything you may need.
The location is great, the metro is very close and it is at two stops from the central station. You can easily go to the city center on foot from his place. It is also very close from the funicular which takes you to the Sant'Elmo castle. The neighbourhood has shops and places to eat around, you feel inside of the Napoli charming. We didn't feel unsecure at any moment. The only thing is that sometimes it can be a bit noisy, but you can solve that by closing the window and turninig the air conditioning on.
Massimo is a really nice host. He came to pick up us to the metro station. He left us some breakfast for the following day and a guide and a map to Napoli. He told us the places we could go and showed us around the neighbourhood. He also helped us with our luggage on the last day. He is very kind and easy going and you can text him in case you have any doubts or problems. I definitely recommend him and his apartment.