He's one of those players who, on the surface, I really don't want to like, because he isn't exceptionally talented, technically, he doesn't really possess any one quality that would, by itself, elevate him to the level of potential genius, and he has a physique that can (with other players) look awkward and uncomfortable and somewhat out of place in the modern game in the positions that he takes up on the field, which is why there are so few players like that in the forward (AM, second striker, etc) positions.
And yet, once you begin to scratch beneath the surface, you realize that it is the sheer simplicity of his game, as well as the fact that he is already incredibly complete for a player of that age, that is the key to his brilliance. Like many of the new crop of German's in this team — and, to be fair, many German players throughout history — he is incredibly effective in that simplicity, and it is conversely that simplicity that makes him incredibly effective.
If there is one thing that Germany has shown in abundance throughout history, it's that you don't need the most skillful, the most individually exciting, and the most talented — according to most pundits, anyway — players to be an exciting and winning team. It is in fact the team that is the star, and each player in it is usually one of the most effective in world football. That's the genius.