As everyone had already said the highlight of Marcello's apartment is the terraces which offer fabulous views of the city.
The location is also excellent, lots of great restaurants, bars etc close by but not touristy. A real slice of Napoli life!
The kitchen is great and had obviously recently been modernised. There's lots of basic ingredients free to use in the cupboards should you want to cook plus tea, coffee etc which was nice.
We did have a problem finding the apartment. Our plane was delayed so we arrived late in the dark, it was raining and we were tired and hungry (so maybe not at our best) the taxi driver didn't know the address so dropped us at the wrong end of the street. We called Patrize (Marcello's mum) who was lovely and very helpful. However when we found the apartment building we couldn't see the buzzer names very clearly (dark and raining - Number 3 from the top for future guests)
The welcome from Nicola Marcello's friend who showed up around the apartment and the view of Vesuvius ensured any problem was quickly forgotten.