Shading on the skirt is what I noticed too. The lack of variation in the skin tones contrasts a bit too much with the niceness of the skirt. It's also nice if you don't outline everything in black, since it gives everything a cartoonish effect, unless that's what you wanted, in which case why draw the skirt so nicely? I think the whole thing would look much much better without all the harsh outlines. I do like the background too.