I have two desires for sites likes these:
They view well from my Treo. Why do I care? Because I normally want to know if I have a book when I am at a bookstore. I hate buying doubles, and this happens every so often. My "plan to read" shelf is quite large, and when it comes to graphic novels I have discovered that I will buy duplicates if I am not careful. LibraryThing looks passable on my Treo, though its search is still not very optimized for a small screen. Shelfari looks awful and its useable from my Treo.
I find out what Friends are reading. I love to know what the people around me are reading. Books get published at an astounding rate, and frankly I can't keep up with it. I also know my authors, but I don't tend to find authors on my own anymore. Once upon a time I would spend an hour or so at a bookstore every couple of weeks scanning for new titles. I still do this once a month, but since bookstores like Barnes and Nobles just use shelf space for well known authors, who I also probably already know about, I don't find as many good books this way anymore. The big book sellers also waste a lot of shelf space with "series", which I am less inclined to read.
Once one of these systems can get enough mass for social networking, I am hoping that they find a good way to allow people to share recommendations. I keep my books in Delicious Library, so its pretty easy for me to mass import my collection into any system.
One annoying point about Shelfari. On the second page after sign up they have a page for uploading your addressbook into their system. There is no way I am uploading my Addressbook into any system. The big annoying part about that page? There is no clear way to jump from
that page to anywhere else in the site. Not having an opt-out makes the page feel like they are trying to pressure me into signing up my friends.
One other note, LibraryThing just feels more human/geeky. The content of the site gives me the feeling that there is a human behind it. So overall I am left with an impression that someone both cares about the site, aka they are doing it for just more then money, and that they are more likely to innovate.
A lot of these new social sites feel to cookie cutter in nature. I like the look and feel of more utilitarian sites. A friend was recently complaining about Craig's List and how its design is non-existent. Personally I am glad that they haven't changed the site.
In conclusion? I'll keep updating the account I made on Shelfari:
My LibraryThing Account:
Uploading my data to two, instead of just one, sites is no big deal. The book social sites are still very much a new game, with no clear winner.