It's OK for a first build. Here's some tips on how to make it better:
-Don't use 1x1x5s for walls in ANY build. It makes it look like crap. You can do much better than that
-Instead, I suggest using 2x2 or 2x4s. Stagger them correctly, and your castle will appear to be a castle
-Try to add some amount of shape to your build. Box houses (or castles in this case) are looked down upon by the community\
-Make some rooms inside of the castle. They don't have to be huge, just enough to accommodate details. That throne room is fine, though. Just add more to it.
-In your interior details, be sure to add some amount of shape, like the exterior. Trust me, that throne would look MUCH better if it had some kind of slope on the arm rests, and some jewels on the top to make it look a bit more royal.
These are just tips. Keep with your build style as much as you like. It makes you original.
