Hi Paul,
I'm no expert on buildings but to me it looks pretty good for a small barn in Russia, can't tell about the scale unless you put a figure beside it, but good luck with the project.
What sort of roof will you be putting on it? Reeds or wood? These building were built locally with local materials and local skill so I don't think it has to be perfect. Poles, planks, sticks, mud and whatever was available would have been used.
I think it will look pretty good once you have it completed. It looks the part as far as I can tell, I like the uneven and rough walls, the uneven planking, should be really good when finished.
Cheers
Al