There is currently a lively discussion in the SL Blogosphere about avatar shapes and what is real and unreal. If you haven't read them, you can catch-up here, here, here, and here.
So, let me say this about that:
As a shapeshifting avatar recently exploring the Grid as femPhin, I gotta say - in the world of SL, so-called realistic shapes are boring. That is, boring if everyone *did* resemble their RL selves. I mean no disrespect to those who want to retain their RL appearance in SL, but it's a fact in my own personal case that I almost left SL because I felt constrained and uninspired. I've tried to find my way in the metaverse for over a year and other than having a few close relationships that mean the world to me, I wanted a little more from my SL.
My recent plunge into shapeshifting has given me a new lease on life in my Second Life. Changing forms and shapes is what keeps me here and keeps me interested.
This is the only virtual world that allows one to change avatar appearance so easily. I like being a human male, a human female, a tiny squirrel (and other assorted tiny avatars), and soon will go exploring as an abstract avatar (neither human nor animal).
SL let's me do this...
A male in Real Life, I can stand on a beach in Extropia - wearing a female shape, hair, skin, red bikini, high-heeled shoes that don't sink into the sand - and chat with my SL GF.