Two wins in a row, their attack has been working properly last few matches.
They were utterly awful against Milan - especially the front two - and deservedly lost against Siena.
Their weakness, like Juve, is finding a way through a packed defence. In the last couple of games they've scored quite early so the opposition has had to come out and leave space.
If Napoli don't get an early goal, all their normal problems will become apparent again.
That said, Inter are so bad that Napoli will beat them no matter how badly they decide to play.