Second Life is the leading 3D virtual world. It's a space where you can be whoever you'd like, build and sell whatever you can imagine, and have fun with others from all over the globe while you explore unique virtual environments, listen to live music performances, play games, shop in the world's largest user-generated virtual goods economy, and much more.
The general idea of Second Life is that you can be whoever you want and do whatever you like but this is the usual case of a really good idea but the worst kind of execution as most of the interface is just mind numbing and too complicated to really provide a smooth "immersion" so to speak.
I guess you could say that it's all about taste but this has the potential to be so much more than it really is and I say this because I used to be on second life but I quit shortly after giving it a chance because it could not live up to my expectations of it, which it very well could have if it was done more user friendly.