Mannone completed his move from Arsenal on the first day of pre-season training as the squad returned to the Academy of Light.
"The potential [of the club] is incredible," he explained to safc.com.
"I have come from a big club but to be honest I don't see any difference in the facilities. From what I can see on my first day they are brilliant.
"To have good facilities where you can work and improve is something every club wants to achieve.
"The base is there and I am really happy to be here."
He added: "I waited a long time for an opportunity like Sunderland, and for me it is a great one.
"I'm very excited. I am here to work hard and to show what I can do."