New illo, what's it lacking?

[Punk-A-Cat]

It seems a little flat value wise.. like, you have a highlight, and midtones, but no real darks and as such no depth to the image. I don't know where you need to push it to get the depth (I'm crap at values but starting to be able to see where they aren't /there/ if that makes sense?)
The hand to the right/ closest seems a little off too.. idk why though.
Really neat image/ concept!