The Guardian has an interesting piece about different approaches to efforts to build a virtual model of London. Naturally, Twinity is included in the list:
Twinity.com, a German company that has already built a virtual Berlin, is building London from Soho towards Westminster and hopes “definitely” to go live this year. Its avatars, which will look realistic as you can transplant your own photo on to your face, will help it build up a strong Facebook-style community in 3D.
As noted, the strength and compelling point is a community in the 3D virtual world.