We were four friends (two couples) in the apartment and were really really happy with it. To say it was clean would be an understatement. The flat is beautiful with a breathtaking view of the city and the volcano. It's not too central but not far off either - we got to know the city by walking to the old town (~50 min.) and got home by public transportation (more than one option). We enjoyed staying a little outside the centre because it can get stressful 24/7 - but we got there every day.
Conversation with our host Valeria was friendly, immediate and helpful. We were welcomed personally and were given some tips and a map straight away. Also if you know Naples just a little bit you value the private parking spot.
Not only would I recommend this apartment but I am gonna choose it again for my next trip to Naples.