We stayed for a few days at Arianna's Place and we had great time there. The apartment is really nice, clean, charming and has everything that you would wish for. Arianna was a really helpful, she helped with everything, - recommended restaurants, solutions for public transport or anything I asked for.
The accommodation is easily accessible from the train station (just use the line 1). The neighborhood - Vomero - is very safe, shops and restaurants are also very close by on high street. (In the close there is a huge supermercato (open in 24 hours), ahh and we can not forget ice cream shops as well.)
If you are looking for a small but cute, clean and quiet apartment, I definitely can recommend to stay at Ariannas place.