The Germany international playmaker joined the Gunners from Real Madrid on transfer deadline day for a reported transfer fee of £42.5m.
"I'm very happy," Sagna told Arsenal's official website. "He's a quality player and we need players like him to come to Arsenal, hopefully he can make the difference offensively.
"Technically he is a world-class player. He can assist many goals. He did it in the past with Real Madrid and Werder Bremen, so I think he's going to do it with us I played against him with the national team and he was the man of the match. It's not good to have him against you.
"Now we are ready to go even further because we started the season quite well, except for the first game of the season. We've done well until now so I'm looking forward to playing with him."
Arsenal will take on Sunderland at the Stadium of Light in the Premier League on Saturday.