Good photo of the girl and her dog, to improve it in my opinion, change the depth of field and blue the back ground some so that the buildings and structures are less visible and less destracting.
The sense of "moment" is present in this image and the obvious character being captured carries some visual impact. Technically, it's slightly over done and could have used a smaller aperature to reduce the overly flat effect of the lighting. From an artistic standpoint, it lacks impact. A worthy entry into the challenge just lacking that something special to make it stand out.