Its funny, I watched a lot of Inter, Juve and Napoli this season and it's quite astonishing what Inter have pulled off so far.
They played Napoli, Juve and Roma away, and got a win (Roma) and 2 draws out of it (Napoli, Juve).
Their fullbacks are ordinary, their midfield (compared to Juve and Napoli) pedestrian with a mix of Borja Valero, Vecino, Brozovic and Gagliardini.
But their forward line is always good for a goal (Candreva, Perisic, Icardi), Handanovic is world class in goal, and Miranda and Skriniar have been absolutely rock solid at the back (especially Skriniar).
Inter fans are calling it 4 musketeers (Spalleti, Perisic, Icardi, Skriniar - with Skriniar being D'Artagnan).
Against the top teams (Roma, Napoli, Juve) they've looked inferior, but never so inferior that you didn't fear them scoring on the counter and then just playing rock solid defensive football.