Nice job, though I must say that the landscaping - foliage - is my favorite part. While the castle is good in design, I don't care so much for the color or texturing distribution. The rocks' overall shape is very nice, but they are incredibly repetitive and uniform and the separation between dark and light bley is much too distinct. The water's color distribution looks very nice, though, as do those trees.
Great detail on all the corners of the castle, and I love your technique of minifigure legs as arrow slits! My only critique is that the rockwork is too repetitive; if you were to put some differently-sized slopes among the 1x2x1 slopes, it would greatly improve it.