This toy can be played by pushing or pulling.  As they pull, gripping the cord, fine motor skills are developed and as they walk along pulling the toy they are using gross motor control in both their arms and legs.  Pushing the toy helps with these muscles as well. 
On their own with this toy, children will develop independent, creative play.  As well, they will develop self-control as they learn to move the toy around immoveable objects.
Talk/Discuss with the child where they have been on their 'journey' with the toy.