Our stay in Napoli was ok. There are some good points about this apartment, such as:
Gianmaria is very accessible and helped us with a lot of tips. Even helped us with a late checkout! Thank you for that.
The apartment has a great location to walk the entire city, or take the subway. Even though the street has a lot of movement, you can't hear much noise of the streets (but only of the streets) inside the place.
The building seems very safe, we had no problems with that.
The apartment has a good air-conditioned system.
The host was very punctual with the checkin.
On the other hand, we had some troubles, like:
The shower drain was very dirty and clogged, meaning our feet would be totally immersed in water during the shower and the bathroom got soaked.
The upstairs neighbors are very noisy. We chose to sleep in the living room instead of the bedroom, because the second floor builded in the apartment has a very low ceiling. In the living room you can hear less noise from upstairs, but still they had a high activity from 11pm until 1:30am both days. There isn't much the host can do about that, but if a guest has problems with noise, it's something that you should know.
For a couple in the end of a 20-something days trip around Italy, we missed a place where we would have a more comfortable time.