An interesting meld of colors in the blurred motion. Use of a great technique with slow shutter and active panning to catch your subject in action and unaware. The child approaching the side adds an extra bit of interest to the shot.
Cropped vertically, eliminating just at the edge of the rear child and giving a bit of space to skate into would have boosted this shot a couple of points for me as it would have put even more emphasis on the chosen subject and simplified the action between the child and man who appears to be trying to steady her.
The border neither adds or detracts from the whole. Bumping from a 4 holder to a 5.