To some it is, and to some, it is not. as some people do not like it who can not afford for VIP. subscription as in my point of view says that there is no fun in barbie girls if you can not afford VIP. subscription.
IMVU Webkins Club Penguin Dizzy Wood Tinierme Build A Bearville Barbie Habbo Hotel Second Life Woozworld Runescape Xivio and hundreds more... http://www.mmorpg.com/gamelist.cfm
Yes, Disney has several virtual worlds, including World of Cars Online, Pirates of the Caribbean Online, Toontown Online, Club Penguin, and Pixie Hollow.