Theres nothing wrong with the black and white, but the color youve chose for the eyes seems somewhat unatural. Especially for the little girl. Maybe try a less intense color.
I personally don't think coloring the eyes works in this picture. But...I don't see anything else to color, either. I do like the picture though! I'd just find a different picture to color, I think. I need to learn how to do that...coloring just a bit of a b/w pic. It's a really neat affect!
Color accent can be a tough call sometimes. When I select photos to do as a color accent the picture needs to really call for it. I think the one you did would have worked better with a softer hue for her eyes and maybe if the little boy was also looking at the camera. I've done a few shots with the eyes in color. Here's one that I picked because I wanted to highlight the fact that the girl and cat had similar eye color. Just a subtle accent works best I think. I never thought I would like color accent, but our customers do so I gave it a try. A lot of times I add the color, look at it and say "Nope, doesn't work".
Here's another that was meant to show the time of year....
Thanks for showing me up Alison... just kidding! Your photos are awesome; showing excellent technique with coloring. I'm still learning and obviously have a ways to go. God I love this stuff!!!
The blue is a little unnatural, but the other thing that makes it look creepy is that the boy's eyes don't seem to be colored. I know there isn't much available there to color, but it really makes the little girl seem different.
I think Allison's photo works because it is subtle and both subjects have the eye color. If just the girl or the cat had it, it would also look strange.
My method for BW/Color images is to start with a color image in Photoshop. Make a Hue/Saturation adjustment layer above it. Pull the saturation slider all the way down to the left. Now your image is gray.
Now Fill the Hue/Saturation layer mask with black to hide all the color. Now your set to selectivly start painting the color back that was "turned off" with the layer mask. Your still working in RGB, your just letting the color image show though only where you want it to.