Thats a great MOC. I love the beam across the inside of the door, I may have to look into doing the same thing for my next castle, though I think I'd do it in brown instead of grey.
I also love that you've not fallen into the same trap as so many other builders and built not only a mottled look into the walls, but portruding windows and butresses as well. I'm not a fan of purely flat walls. I'll admit Stonebarrow has pretty flat walls, but my next castle won't so there!
What's even better, in my opinion, is that you kept the use of Castle Wall pieces to a minimum. This is a perfect example not only of how you don't need to use Castle Wall pieces to build a great keep, but also how you can use them almost seemlessly along with pure brick construction as well.