Although as you can probably guess, this game will be aimed at a younger audience, this is without a doubt, the closest thing to a sand-box MMO which will be released in the nearby future.
Just think about it.
LEGO, the definition of imagination. Something in which even those who are no longer a child can go back to and still have fun playing with every once and a while. The essence of creation itself lies within each and every one of those blocks, and you are the one who has the power to mold them.
I look at this game and i think to myself, if i had a child, this is what i would want him to play. WoW used to be known as the game in which whole familys would play, but that is just a shadow when compared to LEGOU. Your son/daughter will get to build and create, just like you did when you were a child, in an enviorment which is beneficial to them.
And you, as the parent will get a chance to look back at your childhood, and be able to enjoy this game just as much as an 8 year old.
It may not be the ideal MMO that we want, but it is worth taking a look at.