I love this pose as it aligns the entire spine.  Sam Dworkis expounds on the healing value of this pose in his book, Restorative Yoga.  We often find children slowly spinning with arms swinging about their body and it reminds me of when I would rock a baby on my hip to calm myself as well as the baby.
What I discovered after many years of using this pose is that it is an excellent precursor to tree pose.  As you slowly spin side to side you are shifting your weight from one foot to the other.  This allows each foot and leg to take on the majority of your weight while continuing to have the other foot planted for stability.  As you practice this pose notice how it requires both sides of the body to be responsible for stability and allows a child with hemiparesis, one sided weakness, to strengthen the weaker side of the body.  Soon the child will be able to stand on one leg for tree pose with just the toe tip of the other foot for varied amounts of stability.