I'm not certain exactly what you are looking for in terms of comment and since the site seems to be broken I can't see your previous work.
Much of the attractiveness of pictures of children comes from their smooth unblemished skin and changing that to BW negates a lot of appeal.
imo selective color rarely works well. It's something that people do when they first realize they can edit. This is, imo, an example of that.
Ignoring the selective color, the image looks very flat.
Her face is right up against the margin and yet there's space in back of her.
The vignette is waaaay too heavy and obvious to the point of being oppressive.
All the color and the direction of the eyes are all to the left of the image and just to close to the edge, feels like everything is bunched up there. I am fine with just B&W for the child, the child's look here is good, but the background is distracting with the line coming in just below the eye. Tuck in the tag of the shirt as it is white and draws attention away from the face. Instead of the vignette, I think some dodging and burning would add some depth to the face and rest of the image. I would go to a 4x5 crop in portrait, taking all off the back (right side of the image).