We stayed in Stefano's flat for one week - 2 adults and 3 kids (aged 1 ,4 and 6) – the baby was sleeping in our bed (like at home!).
Great flat in a great location : 10-15min walk from the central station where you get the train for destinations like : Pompeii, the Vesuvius, Sorrento, also Line 1 and line 2 of the underground (we used line 2 to visit la Solfatara - a great place to see geysers and boiling mud pool - yes you are in a volcanic area) . The flat is also located a short walking distance to the many buildings in the old town.
It is very well furnished and we had everything we needed during our stay. To be honest, we only had one evening meal in as there are many restaurants nearby (you have to try the best pizza in Italy!)
Stefano was very helpful sending info on trains and buses etc, frequently asking if all was OK.
I would definitely recommend to book this flat if you are planning to visit the majors tourist attractions just outside Naples as you don’t need to get a 1st bus/metro to get to central station.
The whole area around the central station might not be the best location to hang around - but once in the flat you will feel like at home and have a good night sleep before heading for another great day.
Just a little warning about Naples and tourists : be extremely careful with your pockets, bags, jewellery, etc. It is a great place to visit with plenty of things to do (one week is not enough!) but always be on your guard with your belongings.

And the Husband's opinion: I agree with everything, except I'd say it's definitely nearer a 10 minute walk to Central Station if you don't travel with children. I also liked the Courtyard at the apartment. It's old school, and calm, and it means you don't walk straight from the street into the flat. At night all was quiet except for some celebration fireworks one night, and they were not near. Talking to others from the UK we seemed to be the happiest by-far with our accommodation; one retired couple had booked a hotel but were so disappointed that they went elsewhere and ended up paying twice. Even Stephano's WiFi was problem-free and we used it to keep in touch to say that all continued to be well at the apartment.