He's done well with the roles he's been given so far. He hasn't been our main attacking outlet, but he's shown lots of quality and good decision making whenever he's gotten the ball.
As a left winter against Martinique, he showed phenomenal dribbling and crossing, which earned him an assist in that game. He didn't really enter goalscoring positions that often, but that's where David came into prominence.
I won't focus on the 2nd match as that was basically a throwaway, but in the 3rd match, he played as an attacking left full back a la Marcelo. He was less involved in attacks, but he was still a threat going forward, and his speed and strength made up for his defensive deficiencies.
Overall, I would hope that he gets more attacking involvement, but besides that, he has done very well. You can see why Bayern got him.