I just finished up a month long stay in Naples at Daniele's apartment. I have had many positive experiences using Airbnb but this was by far the best. Daniele and his girlfriend are very kind and hospitable. Daniele does a great job making sure you have everything you need and is very responsive if any questions or concerns arise.
As for the apartment, after being there a month, it really felt like home. There is tons of space, the pictures do not do it justice. My girlfriend and I were extremely comfortable — an additional two guest would have been no problem at all. The apartment is perfectly clean, the bed is comfortable, the kitchen is a good size and well-stocked, the bathrooms were spacious, and the AC kept the apartment very cool. As for location, I do not think I could imagine a better place to stay. You are in the center of everything and can easily walk to almost anything you would want to experience or eat. The street stays relatively quiet and feels very local.
I cannot stress this enough: stay here, you will not be disappointed!