I just got back from staying at Old Naples for 5 days. It all went very smoothly, from the "check-in" to leaving. I didn't get to meet Matteo or Teresa, but everything is explained in a guide in the apartment. It was super clean and cool when I closed the shutters. There was just myself, so I had lots of room to move around. I didn't do any cooking, but appreciated the fridge and being able to make salads.
The location was perfect for me as I was able to walk everywhere, including the train station, the Archaeological Museum and even up to Capo di Monte. Lots of great restaurants nearly or down in the spanish area.