There are some very strong points in this drawing, but in general there are a lot of things holding it back from its full potential as a drawing. Luckily quite a few of these issues are relatively easy to fix and/or rework. Right off the bat you have some good color choices and everything used works well together and communicates a very desolate feel. Those rocks and the floor in the foreground and mid-ground are very well drawn and rendered and the sky background is very interesting in the large clearly defined strokes used to make it; it keeps the grey interesting and makes the sky feel more alive as opposed to solid colors or a smooth gradient. The vagueness of the sky should be carried over more to the buildings in the background, right now as they are with the hard outlines make them way too clear and defined; just by removing those lines you will go a long way in pushing them back and adding to the sense of distance in your drawing, you can further the sense of distance by washing out the colors a bit more. The buildings further in the back are in a good place right now, but I would recommend throwing in a few more and have them run off the page to the left and right to give a better sense of continuity and scale for the city.
The characters up front have a lot of problems, they're costumes are well shaded and drawn, but their poses, proportions and placement are a bit awkward. The crouching girl right now needs some work on her body structure, the way her legs are don't look to line up with her waist properly and the knee on the left needs to be made larger and come out more to better capture the foreshortening effect. the girl on the left's anatomy could use some work as well, women's hips are generally drawn an equal width to their shoulders to communicate femininity. The fabric of her robe could be drawn a bit more organically, right now its very up and down and rigid looking. She's also very symmetrical which is pretty boring and sucks the life out of her; try making some adjustments to her pose to better compliment the crouching girl. The crouching girl is looking off to the right somewhat bewildered, try playing that up and have the robed girl reacting to that as well, things like that add to the narrative of a drawing.
I hope this helps in some capacity, keep up the good work.