The former Manchester City midfielder joined Napoli earlier this summer in a free transfer.
McTominay told Il Mattino: "Surprised by KDB's arrival? Absolutely not. Because I was aware of how strong Napoli was, of the club's ambitions.
"A player with incredible qualities. But above all, Kevin is a good person. Having him with us will be an injection of talent and experience. We can't wait to play together. We know each other very well; we've played against each other so many times in the Premier League.
"We've experienced unforgettable matches and also tough moments given the rivalry."
McTominay also had a word for teammate Pasquale Mazzocchi.
He said, "Pasquale is a great person, a fantastic guy. He works so hard every single day, he's humble, that's what you should always be when you step onto a football pitch. And he's a gentleman, even outside of football.
"That's precisely why it's a pleasure to be with him. My Italian? It's still poor. His English? Zero on the scoresheet."