It's great, haha. I've got two books on it xD It's helpful for real life applications too, but I enjoy using it to make well-rounded characters.

For example, it gives a look into a person's potential abilities, the things they can do when they're emotionally healthy. For Cas, he has the potential to be a great altruistic leader, but right now his ambition is stifled because he never receives any praise from Atlas. Feeling useful and loved is key to 2s, and because his father makes him feel worthless, he doesn't have the confidence to practice being a leader, even though he would be a natural. When he starts getting the affirmation he needs from another source (i.e: Iris later on, I'd assume), he'll have the energy he needs to step up and be a good king.

It's little details like that that help to bring the character to life ^^