Several of us over on the game forums play this.
You can play the game for free, but you are only allowed to advance so far in certain areas.
The paid game can take you all of the way up. Right now I use the $60 a year promotion when they have it.

But, you can pay monthly or use game cards from places like
Best Buy to pay with.
I really like the game, though I don't get much time to play right now. A lot of us are playing just a little, while waiting on a new land to come out. We've all got grandmasters who are just helping in the game right now or 'farming' for stuff to sell.

Or bringing up our other school characters.

You can have up to six characters on each account.
You can have full chat, almost full chat and menu only chat depending on your family member playing. If you plan on staying nearby with your young family member playing, the near full chat may be a good way to go. However, despite some words being absent from the dictionary some bad things can get through. But, the limited chat through the menu only items can mean that the player has a harder time making really helpful friends, as most of us with free/full chat won't add them to our friends list. Unfortunately, non full chat members have a way of jumping to us at bad moments. And, there isn't any way to stop them some times without stopping your other friends as well.
That said...the game as a whole is enjoyable and keeps you on your toes at times. lol You learn how to plan your decks for your battles and how to use what you do have then. You can buy clothes and furniture and tools and win them from boss drops as well. You can also buy houses for each land or houses for each school. Depending on how old your child is they may enjoy it a lot! But, I would recommend that you or another adult play along as well. I find it fun to play with family and friends.

The only drawback is you have to have separate accounts to play, but there is a family plan for about $10 or $15 or month or so..(don't quote me on that! lol) Look over some of the topics under the non-disney forum under the game forums and use the search feature to bring up old topics under the game.
Feel free to pm me if you have anymore questions or just ask them in the games forum.
Btw, the game was rated one of the top family games too for this year.
Kim