Zomygoodness, how big is that waterfall? I mean, it's big enough to dwarf a giant castle! Or maybe it's a really small castle, made for really small six inch tall people-things. Or maybe it's made for REALLY little people, and that waterfall is just a little stream going down the mountains into a lake? GASDOO So many creative juices flow out of this painting!! I love it!!
Actually, just one little thing: There are no people, or signs of people. If this place is abandoned (as if ) then sure, but otherwise I'd suggest maybe a cart on the road, and some people (dots...) on the bridge... otherwise, yeah.
I´m not a pro, but maybe you could add some bright colors? Like a flower field somewhere? (oh yeah, girls and flowers^^ But I saw an impressive one in my hometown. [link] )Something like an eyecatcher in the lower area?