The apartment is really nice. big volumes and nice decoration. If you're travelling by train it is very close to the station. Everything went smoothly with Dario. He was not there when we arrived but is friend Francesco too care of everything.
As for the location, travelling with 3 Kids, I've never felt so unsecure (dealers and hookers in the backstreets !!!!)
But I don't know if there are many safer areas in Napoli. If you want to visit Pompei or Vesuvio or almafatic coast, I world suggest to stay out of Napoli and its immediate surroundings .