Rear curtain sync is an exciting and fun technique to experiment with.
It does, however, work better when the background/foreground is dark and the target is light. As you can see in your shot, you had what is in effect a double exposure concerning the model's legs and the water patterns. Balancing the lighting in rear curtain sync is the tough part.
Keep it up though. You can get a different and exciting look using rear curtain sync!
You got the composition right!