I really like how it looks more like a fairy-tale illustration than a render. I'd be tempted to make the viewpoint even more extreme, and have the camera maybe looking upwards at a hawk or eagle or ridiculous makeshift flying machine in the sky above the castle. That way the castle would look like it was just incidental to the focal-point in the sky, and you could have a suggestion of all sorts of activity in and around the castle, but not have it the point of the picture. Just my 2 cents' worth.