Ahh bella Napoli.. If you have been to AND enjoyed northern Italy (say Roma or Firenze or Milano) then try you luck with bella Napoli.
Napoli is a dirty, loud, chaotic, poverty-stricken, crazy kind-of-town. The traffic is intense, the garbage is piled everywhere, there are burnt-out buildings here and there (even churches) and if you own a car in this town expect it to be dented within 48 hours of its purchase.
Napoli, city of pizza (try Michiele's or Matteo's for the best slices in town), city of squats (otherwise known as Centro sociale in Italy - if this is your thing ask around for either the T.N.T. or the Damm), city of thieves (try buying a digital video camera by the train station and you'll see what I mean).
Napoli - don't trust those gypsy kids playing the accordion. They'd just as likely pick your pocket as take your charity.
Napoli - city of magic moments and scenic slums... I love this town.
The port has ferries to Catania, Ischia, Sorrento... The bus station is located at the port and has busses to Pompei and Mt. Vesuvius among other less touristic destinations. There is a hostel called Hostel of the Sun that is very loud and costs 18 euro (also located near the port - you can find it on the net).
Be very careful with your valuables.
It is not uncommon to have purses and or cameras and or other shoulder carried items stolen by men on motor scooters!
The local Mafia is called the CAMORRA - they run a lot of drugs and are quite hard to spot...
There are no parks or green areas in Napoli.
It's winding, narrow cobblestone streets are a good place to be run over so be careful.
The best parties in town all seem to happen at the Piazzias (where since this is Europe) you can drink on the streets (and also smoke joints, although it's not legal - but the cops have better things to do). The cheapest beer can be bought in supermarkets or Alementari or from illegal vendors on the street.