The Germany international has made a superb start to his Arsenal career, scoring in three successive games for his new club.
"He looks happy to be here and he has integrated into the team," Wenger told Arsenal Player.
"He is a happy boy, [with a] happy nature. Plus he's a good communicator, he speaks English quite well already. That helps. Overall, he's a positive character.
"I believe as well that today in the modern game, to be a top level player, you need to be a top-level worker first. There's no room anymore for anything else. He understands that."