This is quite impressive, and I have always been a huge fan of complete city mocs myself. However, I am lacking the bricks myself, so I jump at every great city I see online. This creation is quite grand, and I have to say I could not find any flaws in it. My favorite details (and this was tough, as there were so many) were the armor on the guards, the construction of a section of wall, the arches and other creative architecture, and the old, huge tree in the courtyard. I also like what appears to be three bandits or a few bandits with a hostage being confronted around the side of the castle by a guard.
Failure is not an option.