It seems very professionally done, specially the flow that it creates from left to right, and how the image doesn't just focus on just one place, it pulls your eye from left to right. great job on the water, and the waves, seems very realistic. Waterfall is really amazing, specially the glow it has makes it look realistic. Nice job on getting the foreground elements with the wood piece and the rock on the left. But I think that you should focus on the castle's detail a little bit more, the rock and the waterfall under it is more detailed that the castle itself which grabs the attention to the rock, not the castle.
Great job with the lighting of the castle, and the mountains.