Horrible kids

I'd say that the shading is very neat. It's very simplistic and very clean. I really like how the background adds a lot to the piece but at the same time it does not take away from the drawing itself. Again, very simple and clean.
It has a lot of style and I'm loving that facial expression!

Of course, shading will always get better each time you practice it, so I wouldn't be worried because you're on the right track.

The only thing that looks kind of awkward to me is that small hump in the back. I'm not sure if it's a lump of fur or where the shoulders pop out.

Overall it's very well done. I love it!