Can't belive noone commented on this. I missed it because I was drunk when you posted.
Nice work, I like it alot
But as with all CD project, the houses looks jagged and the terrain texture is blurred.
The city looks much like my Burgenos. The fortifications are good. There won't be anyone raiding this place. Have you considered a moat around the hill? A canal from the river, round the castle and down to the harbour. It could be a dry moat with a dam by the river. Open it and presto, instant moat.
The harbour is well protected from the sea, a chan across between the island and the mainland stops the ships.
I would add a tower or a bastion to the north wall, that seems to be the main angle of attack, and har a long strech of wall for aming catapults and fireballs at.

/Hoel -has an intrest in fortification