Nail the lighting like everybody is saying. Also, the specular/gloss on the bricks are too high. Also check the size of the bricks, they are big compared to the concept as well as the size of your scene. Look at the door and the bricks around it to get a better sense.
I'd say that the lines are a bit too random at the moment. Think about how these bricks could have broken apart; some bricks will have cracked along the edges into the middle. Search for reference pictures of bricks to see what I mean.