Sergio's place was the perfect spot for the Napoli portion of my trip. I walked to his place from the train station and he met me personally and got me situated right away. He was upfront about the parts of town that were okay after dark and I had no problems at all during my trip. His place was spacious for one person, but would sleep a family of four comfortably with the bed and the futon.
He steered me to Sorbillo's Pizza, where I experienced the best pizza of my life! But honestly, the pizza portafoglio that's folded and handed to you on the street for 1-2 euros is better than most of what I've had back home. (You may want to try a couple of them before you hit Sorbillo's, just so you can establish a baseline.)
The shower and hot water were fantastic. TV and WiFi were great as well. All in all, a perfect place to spend a few days in Napoli. You're probably not going to love every street you walk down in Naples, but the main streets are fine and the apartment is close to Porto Nolano Station, where you catch the train to the Pompeii Excavation site.
Bottom line, Sergio is a great host with a great space... he had good communications with me before and during the trip and I highly recommend his place!