I played Lego Universe for less than a month, as a free player you run out of new things to do after a few hours and you got stuck in one of the available worlds with no way of getting out. You can kill monsters for days or build your own castle in your own planet, but you can only reach 10000 cusps and buy only 10% of the thinks available.
It was 10 dollars/month as well but my nephew didn't want to suscribe, he loved killing trolls and monsters but he got bored too and we left it.