Read an article about some 35 year old man who purchased a virtual business within the Entropia Universe for $350.000! http://gizmodo.com/5693093/man-who-paid-335000-for-virtual-real-estate-explains-why I read up on it and it sounds like its playstation HOME meets WOW or something, and with a fully functional economy. But i couldn't get a grasp on what you're suppose to do besides just live in their world, virtually. From the description you get to chose the planet you'll be born on (calypso or rocktopia), and explore them both.
It also seems as if real life businesses are suppose to market themselves in this world (like PS HOME) and you'll be able to purchase music and videos etc.

Does anyone have any experience with it? Do you do some sort of quest like missions or how does it all work?

http://www.entropiauniverse.com/
http://www.planetcalypso.com/home/
http://www.rocktropia.com/

It caught my interest too, but I didn't actually play it. It inspired me to play an old game I played a while ago; it is similar but focussed on Kingdoms and war. I became Regent/Monarch of my Kingdom by the end of my second week, killed all the inactives, and then successfully took them to a 6 day war, and realized why I quit in the first place; and quit once again. I also saw that my former Alliance in the game no longer dominates the top 50 Kingdoms; and the associated IRC channels are much lower in population now.