If used sparingly, in the right setting, at the right time, for the right purpose, it can have a powerful impact. If over-used it can be a bit, well, naff.
It works fine here.
One of the most powerful uses of selective colourisation in the movie industry was in Spielberg's Schindler's List, in which the red coat of the little girl runs through the film until we see it lying discarded after her death in the Nazi death camp.
Thanks Donald, I have seen some images where this technique was used too far and yes it results in looking quite naff. The image I used was not purposely taken with selective colourisation in mind, I just thought I would experiment on that one.
In my opinion, (and that's only my opinion!!), selective colourisation should be used to draw the eye, and your attention to the subject. There's a pretty good example of it in a post titled "Red Hair in Black". Here, to me it does the opposite. When I take a glance, all I see are flamingos, and the girl becomes washed out in gray with the rest of the background.