1. You can go to sleep whenever you damn well want. You can go to sleep at 4 AM if you want to.
2. You get to hang out with whoever you want. You don't have to hang out with someone's lame-ass kid just because your parents and their parents are friends.
3. You get alcohol.
4. You don't have to ask anyone's permission whenever you want to go somewhere. You just go.
5. No one is making you practice your penmanship. Your handwriting can be as shitty as you want it to be.
6. You won't be socially ostracized by your peers for wearing the wrong brand of shoes.
7. You get to own a car, and drive it anywhere you want. (Please don't combine with #3.)
8. Two words: Gym class.
9. You have way more tools and techniques for dealing with the disappointments that life slings at you. They're still there; you're just so much better equipped to handle them.
10. When you're a kid, you have no control over anything that happens to you. Every single event and decision in your life is the result of someone else's judgment. When you're an adult, you call the shots. Everything that happens to you is of your own choosing. Your life may suck because you made shitty decisions, but you can still own the fuck out of those decisions. (Besides, you had fun making them, didn't you?)