This is the first digital piece I've ever faved. There's a kind of contradiction there, in that it is a purely digital work with a medieval subject. That makes it rather interesting...
Wouldn't call this piece "photorealistic" as others here have, but it doesn't need to be. To me it looks like something painted in acrylics or gouache. The water in the moat would not necessarily be that blue...blue water is in the ocean. A small pond (which is what a moat is, basically--the castle is the island in it) would be murky & greenish. But overall, a great piece.