I agree about the piers. It looks too much like a fade rather than the effect you are going for (which I believe is a sloped pier descending into the water). You need a harsher line where the pier breaches the water's surface.

About the street layout - I have similar trouble making mine look convincing too. The map itself looks awesome though, it's really well crafted and clear. I like the style a lot.

The only other thing is there appears to be a slope down just beyond the river within the confines of the city. I dread to think what happens on the rare occasions that the river bursts it's banks.