Nice shot. My only suggestion is to get in tighter and really focus in on the hands and laces. Pretty much just hands, shoe, and laces in the frame.
I find that when selective desaturation is used its best if what is left in color takes up a significant portion of the frame. Naturally there are exceptions to this but generally... :)
All I can say is "Awwwwwww"! I love using the black and white with the purple shoe laces. I don't know what this effect is called but great use of it here :-)
Great photo! One day I'll have to learn how to bring colour into a photo as something as intricate as you have done. I guess being stuck with post processing software that comes free with the computer won't help me.