It isn't free.
They called it free realms for a reason
kotaku says its free
There are plenty of free MMOs aimed at the kid market out there, but they all tend to share certain bad traits. Shoddy graphics, poor-quality interfaces, and an overall lack of polish. SOE is taking the social children's game concept, applying a World of Warcraft level of polish, packing it with personality and mini-games, and unleashing it upon the computing family for free.
you have the option of paying for little extra items.
SOE is offering a low price point. In fact, you can play the game completely for free if you're willing to put up with ads and choose to purchase smaller items in microtransactions. Getting rid of ads has a pretty low pricepoint as well at only $4.99 for one account or $9.99 for a family plan of five accounts.
If you're looking for the next big thing in massively multiplayer gaming - we mean really big; multiple millions of players big - look no further. Sony Online Entertainment's Free Realms, a free-to-play, modern-fantasy, mini-game-heavy MMO for PC and later PS3, aimed at kids, is that game.