Kendama trains the eye, mind, and the hands of the user. Various tricks on the Kendama proves this, especially when the user strives to reach for perfection upon a specific trick.
Kendama is also a great alternative to take some time away from electronics such as iPhone and iPad. I am not saying that Kendama users should completely avoid such electronics. What I am trying to say is that Kendama is another way to have fun while being trained other than electronics.