You could have incorporated more detail into the waterway, it looks a too smooth, without any ripples from the boats or other wise, but you have intended for it to be this way. Amazing detail elsewhere, in the houses and trees and such. You should be proud, and your friend is lucky
I really like it, especially the fact that you did it with pen! But there's something about the river that looks a little to flat and plain so that if the boats weren't there I would simply think it was an empty street... even the way the boats sit on the water just makes them looks like they're stuck in dry land. Just a random thought about it, but as far as skills go I can't hope to compete with you so you don't have to pay much attention to me!