There are pros and cons to being a child.
pros:
Innocence.
No responsibility.
Few consequences.
More free time.
Seemingly endless amounts of energy.
Fewer standards and expectations - you can do weird things and it's okay because you're a kid.
Cons:
No freedom or autonomy; your parents decide what you do, how you do it, when you do it and what you wear while you're doing it. And yes that includes curfews and bedtimes.
School, homework and chores.
No money.
You can be punished, this could be anything from having your possessions taken off you to a spanking depending on your parents and what's legal where you live, which really, really sucks. It's not okay for adults to hit one another but a parent can totally smack their child.
Bullies; if you harass or bully someone as an adult you can go to jail, yet the worse that might happen to a child is a good telling off or maybe even a suspension from school, but most likely nothing at all, and bullies can be cruel, really cruel.
Puberty sucks big time.
You're restricted by age restrictions on pretty much everything. So no alcohol, gambling, voting, sex, smoking, rated movies/games and so on....
Now when you become an adult you get rid of age restrictions and parental authority, so you can do more things and can't be punished by your parents anymore, although you trade this off for the law, but it's still better because you can't be assaulted anymore and people need a court order to remove your belongings, and that's only if you get into debt. You're also better protected from bullies too and no longer have to go to school, yes there is work but at least you're being paid for it.
As for freedom and autonomy, yes technically you have more. You can now decide what to wear and how you want to do things, but money plays a massive part in how much freedom you actually have, and this I believe is probably the most important factor in determining how much you will enjoy adult life. Money lets you do all those things you wanted to do as a child, without it you've traded some of the pros and cons of childhood with some of the pros and cons of adulthood, only you've way more responsibilities and less free time.
So adulthood can be good or bad, it depends on how much money (freedom), you have and how willing you are to do things without caring what other people think.