DAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAMN!
I wish I had that kind of skill ^_^'
The only thing I can honestly say looks off is the depth. They look kind of like they're standing 'in the wall' and the radio doesn't have any dimension.
It's also very flat. Not a whole lot of variance in the angle of presentation. It all just kinda faces forward, and that's a bit boring. But if say you were to mayber turn the sterio to the side a little bit and provide some more dynamic shading on the characters it'd look a lot mor dimensional and 3D. Plus it'd be more interesting to look at ;)
And her right knee, too. Because of the way you placed the shadow her knee looks more like the back of her leg.
Other than that it looks good :D
Keep up the good work ;)