It's a good start.
Firstly, the the textures you have given it are terribly easily recognisable as repeat offenders. Their scale makes the castle look tiny, and the lack of actual modelled details doesnt help with the scale.
Do you have a reference to the castle you are making? This doesn't look like a castle, more of a fort (at the moment made out of carboard, spray painted with a stencil and places in a crazy wolfenstein game) that has no sense or way that people could live, fight and procreate inside or around.
What I would suggest, look up some references ( for example, Weider's fantastic castle that he made, theres a tut at
http://www.the3dstudio.com search google e.t.c ), figure out the actual style details layout feel environment and complete the modelling of all the details necessary, and instead of throwing on a default texmap, finish the model first, and see what kind of textures should be applied and maybe make your own, or go procedural. There is a world of opportunities, it looks like you've done a rushed job in the hopes of getting something grand. Think of modelling something grand, expect it will take time, effort and dedication and it will come about quicker than you think. Each time you do it, it will get quicker and quicker and soon you will be a jedi master.