only big error I see is her nose.
I think it is a bit too high (or other said it ends too soon).

as a basic rule the space between the mouth and the nose is never bigger than the space between the mouth and the chin (normaly it is a bit smaller).

otherwise its nice it kinda reminds me of the oldschool stuff (think captain future, heidi).

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Wer nicht vom Meister lernt, lernt nie etwas.

1st of all I agree with Giam on the nose. It's a touch to far up from the mouth. But, I think what's really making this look not right "is the perspective" it doesn't match up just quite. I tried looking at it up/down point of view, it' might be ok if you intended this a overhead down view from above-slight back/left. But, if you made this even more a difficult pose like a direction down super close overlook the nose distance wouldn't matter (due to depth).

The left ear is a bit to close to the eyes. I'd move it about 1/2in outward from the placement. Since the left eye is closer in view the ear should be a touch farther out or the other ear (the one you don't see) would be right there.

I can only determine this is a boy, cause of the eyebrow and the eye shape
(even if the hair is a bit puffy). If your going for a female face you should define the eyebrow more making it thin (smaller, narrow, or thin) or make the eyelashes more pointed/feathered.