Looks nice.
Walls over rivers are tricky, they would more likely be a tower bridge. The purpose is to control the traffic on the river for tax collecting and defense.
You should wall up the SE edge of the keep, the walls are not just there do stop an assault, they are there to protect the buildings from artillery. As it is, if the enemy takes the SE bank they could fire straight into the keep. Not good.
Also, there are very long stretches without towers. I don't know how well defended this city is supposed to be, but i would put some hanging towers on there and have sizable bastions on all corners.
Cheers