I tried that, and as a trading card game it's pretty good.
Unfortunately, Sony has utterly crippled it:
* You can pay extra (beyond subscription) to get super-cards.
* You are not allowed to trade most cards.
* Especially not the bought cards.
* Because their chat censor all numbers, semi-dirty words, words that from a distance can look like a semi-dirty word, it is completely impossible to converse with your opponent.
Can't you pay extra in any TCG to get super-cards? That's the whole business model behind trading card games.
I'm 100% sure that the only cards you cannot trade are the promotional cards you get for free. All the bought cards are tradeable inside of the TCG. You cannot trade in the 3d world, you have to use the TCG interface.
The chat filter is pretty restrictive but since it is a kids game I think their hands are tied if they want to keep it safe for kids.
If you like trading card games, it's worth checking out.