Your color theory and lighting/composition are actually pretty good, so you've already got a good starting point. I like the overall design, and my only real crit is that you stayed with a pretty loose brush the entire time, which works well for the fur textures, but not so much for the bars or bricks. I'm assuming this was a speedpainting though and based on your working knowledge of color and light I doubt I'm telling you anything you don't already know.
It's really good!
It's really good!