The feature is tricky. Obviously, Napoli is the stronger side, but I won't be quick to give them a win. It won't be easy to win at the San Siro. Last season, they won AC Milan at the San Siro, but I'm sure they can do it this time. After AC Milan's shocking home defeat on matchday one, they've bounced back and are on a three match winning streak. So it's kind of difficult for me to give Napoli a win, but over 2.5 goals looks feasible.
AC Milan in the previous season was very weak at the time where Napoli was rocking. This season AC Milan looks better so I think analysing the situation when taking on consideration the previous season might be erroneous.
It is true Napoli still looking in good shape, having higher odds in bookies although playing away but I think AC Milan could drive them to a draw if they play correctly. I am a bit influenced by the result of Napoli against Pisa
I believe that this big match will be exciting and that Milan will beat Napoli! If that happens, we can consider Milan a contender for the Italian championship title.
That's my impression: Milan will win 1-0 in Max Allegri's typical style of play.