The former Arsenal keeper joined the Black Cats for £2m earlier this month and is one of several new faces at the Stadium of Light.
"It's a big positive. It looks like a new era, the beginning of a new project," Mannone told reporters. "I'm really happy to be involved in this project now.
"There are quite a few new players in and it's good that we've all come in at once at the start of something.
"The lads who were already here are helping us quite a lot. I think we've already made great progress in terms of getting to know each other and starting to form a team. In another month, we will be the team that the boss wants us to be."