The apartment is clean, very comfortable and pleasant. The location is wonderful: easy walking to many of the major sights, a block away from a very happening neighborhood street scene, not far from the subway. Claudio let us stash our luggage even though we were several hours early for check-in.
This is a nice duplex -- it worked well for our 20-year-old son upstairs with plenty of privacy and his own very nice bathroom and us with our own privacy down below. Would work well for two couples. The bathrooms were clean and functioned well. The kitchen was very useful. There are several small food shops within a few block radius, and we found some wonderful non-touristy local food and wine stores about 10 minutes walk away that were delighted to be helpful and friendly to us, so we had several delicious meals at "home".
The University is around the corner, so there are lots of young, hip people always about, with plenty of bars, cafes and hangouts going, some late into the night. Its fun to stand on the balcony looking at the street scene. There is a club across the street that starts going at midnight, but the crowd is cool, and since the bedroom is in the back we were not disturbed when the front windows were closed. There is an air conditioner so this should not be a problem in the summer. We heartily recommend the restaurant Pulcinella up the street (make a reservation when you walk by).
We thoroughly enjoyed our week long stay, and would gladly come back to Napoli and this apartment again without hesitation.