Hey there!

So to start with, I just want to say that your organics and terrain look lovely. They're perfect the way they are. You have a good density of trees around your plot and your terrain gives good structural opportunities. I think in the ravine, you may want to mix in some other blocks in with the stone. Maybe just some cobblestone, but you can be more creative and mix some clay, andesite etc. Your choice! :3

Your structures are the main problems. I think the tower itself actually looks pretty good, apart from the stone slabs as detailing around the middle. I don't think they really work there. Without them, it looks a little bland - may be an idea to switch the netherbrick into some other stone type block, so it blends more with the rest of the tower and therefore gives the impression of detail.

I think the smaller structure you have is a little random and out of place. Another structure with a similar style to the tower would be perfect :3

Good luck!
- Dutty :3