Wow, I cannot believe I have not commented on this before :O This is brilliant, the rock's the special texturing of the Castle and colouring, its really amazing. You must tell me how the 'BrickVention' went?? Is that the Lego show up in Auckland?
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.