I love being an adult (I'm 25 btw)
But I also loved being a kid and a teenager- so I can't really say if one is better than the other.
As an adult you can do whatever you feel like, so long as you are willing to accept the consequences of your actions. You don't have to do chores, eat your veggies, do your work - but likewise then you could just end up living in filth, as fat as a cow and unemployed. So for the most part if you had good parents, what this really means is no one is watching your back all the time anymore- you have to do the "right thing" because it's good for you, not cause someone is telling you to.
As an adult I have a hard time feeling bad for any teenager who complains about their parents or their chores - think your parents are annoying cause they tell you to get off the computer and clean your room? or perhaps you think your parents are unfair cause they won't give you 20 dollars to go to the movies with your friends? Just wait until you own your own house and you constantly have to clean all of it, take care of the yard, worry about bills, pay off loans, keep a decent credit score, physical health, etc, all while working at least 40 hours a week.
I find I have a lot less time to do random crap as an adult cause I'm too busy just micromanaging all the different parts of my life.
Now this isn't to say being an adult isn't awesome - It's great having control over your own life and for me I really love my job and work with great people that I consider friends (and family, my sister works at the same office lol), and of course there is the joys of being married (which I'm sure you can all imagine
but sometimes it would be nice to be a teenager again and have my major worry be the next calculus exam or something LOL.