Hey there :3

Firstly, terrain. I like the layered terrain you have (the part under the castle), it works well with the plot. The cliff area you made is a little too skinny and doesn't really lead into anything on the plot - it lacks purpose a little, so it doesn't really look as nice as it could be! I think you need to expand on this area, make it a lot longer and have a way for people to get from the ground to on top of the cliff!
Your plot also lacks in atmosphere. You have spotted cobble stone all over the ground, which looks nice, but I think you also need some more dense cobble, maybe make some pathways leading from structure to structure.

Secondly, organics. I do like the tree you have made; you should make the leaves look less like spheres, though. Right now they look too world edited. To overcome this, use a high air percentage in your brush!
Eg: //br sphere 10%leaves,90%air
That's the one I use all the time!

Lastly, structure. The mini structures you have are cute but a little uninteresting. It would be nice if you gave them some interiors, if they are what I assume they are! (Stalls?) You could use some chests/crafting tables/plant pots etc to add some little decoration!
Secondly, your castle. I really like the frame work you have going on. It's simple but really effective! Some of the detailing, however, needs a lot of improvement! I like the cobble walls as detail, but not as many as you have used. Same goes for the cobblestone stairs - it's a little strange to build the detail 'inside' the wall, instead on 'over' the wall. You're also going to need to be a little more experimental with your palette - having it all grey is a bit too plain. Try some coloured clay, or some really funky textures!

Good luck!
- Dutty :3