The Undercity

The perspective is off. The background structure has its viewpoint in the upper right part outside of the frame whereas the two buildings in the front have perpendicular lines. They both look misaligned to each other, too. The foremost building alone has some issues which makes it look a bit strange. The vertical line to the right of the "open" sign is tilted to the left, the ledge below the "girls" sign should taper the other way round with less strong angles. The pipe stuff below the guy on top of the building also seems misaligned to the ledge between them and the "thru city entrance" sign. The walkways kinda like are all over the place. And the buildings right below the downmost walkway don't read well. The yellow light in the left corner below looks rather distracting, too. About depth: The middle structure with "Jakes" on it seems a little too big. It's just flat and not too interesting to look at. Right now the line completely blocks the view.
Compositionwise it cuts the piece into two equal parts where rule of thirds should be applied. And it seperates the picture completely. The view should be guided gently from the bottom all the way up to the ship, which seems to be the important part (and I really like that).
Sorry if this comes down as harsh. I really like your characters. You seem to have moved well beyond the basics already which makes the mentioned issues stand out even more.