Napoli is an amazing city with tons to do and is easily navigated. I was a little apprehensive after hearing some reviews of a 'gritty' city, but aside from some graffiti and liter which EVERY city has Napoli is filled with amazing people, food, and great sites.
Insider Tip:Most Do's: Pompei, Vesuvius, Capri boat tour (80 E best money you'll ever spend), Sorrento, Positano, and Amalfi. There is a local beach about 20 cab ride from hostel called LaGioia GO THERE! And eat at Matteo's Pizza. There are also parties at the main Piazza every night.