Well it is, but your particular style looks good that way. At least to me.
Problems:
- No light effects on the shirt.
- No shading on the shirt.
- Minimal shading in hair.
- Red shirt is barely showing. It needs to be darker. Needs shade.
The choice of colors don't "excite" me, but they are ok. Better color cooperation(contrast) could improve this piece.
EDIT:
Do you use Photoshop to color??