I have long fought duplicating my reading/reviewing efforts on more than one book site, but, ALAS, I now find it necessary to do just that.
Shelfari is my site of choice. I have spent more time there, and find it much less cluttered than goodreads . Unfortunately for me, goodreads seems to have more author activity and traffic. I have also noticed that book bloggers and reviewers seem to prefer goodreads .
With that in mind, I am in NO WAY abandoning my Shelfari. I am sure I will always prefer it because it was my "first love", but I will now post book reviews and ratings in both places.
My Shelfari Profile
My goodreads Profile
I have spend a few days copying reviews from Shelfari to goodreads, and have done all of my titles A-L. I will work to get the rest on there, and then will continue to maintain both sites.