My only problem with the dragon's wings is they seem somewhat small—a mistake I see in almost every iteration of a dragon. A creature that size must have wings of massive size in proportion to its body to generate enough lift force to accommodate its weight. Either that, or it is substantially lighter than it looks. Though, considering this is fantasy, I guess they can get around that science with relative ease.
[EDIT]: The wing curvature also looks somewhat flat (I must admit it's hard to see though). For an animal, or even a plane, to fly, the wing must have a very slight upward arch to get lift under its wings. If a creature has flat wings then it must rely on rapid beats, such as that of a bee or a hummingbird, or slower beats with a drastic wing size to weight ratio, like a butterfly. But such quick succession of beats is impractical for a creature of a dragon's size, as it would require an obscene amount of energy and mucle power. That's why you notice that the lager flying animals rely on gliding far more than they do beating their wings. But to glide in that fashion, as a dragon obviously must, they need an appropriate wing shape and surface area. In fact, that was the Wright brothers's great breakthrough. They discovered, to get their planes to fly, they must curve the wings so that the airflow hit the underside of the wing provideing lift force. These dragons, as it appears to me, need slightly (or perhaps drastically) larger wings, providing more surface area, and need more overarching curvature of the wing, to provide more lift force.