More than a tool, a community
I am personally, a HUGE advocate of Goodreads. I use it almost daily, looking up recommendations and opinions about books on all sorts of topics. I love that Goodreads will recommend books based off of things that you've read, and I've found a tremendous number of new materials based off of those recommendations. I would say that perhaps the one negative is that it is a community where people are free to post whatever they wish, so there are occasions where you see some language or personal opinions that can get a bit jarring. However, I believe that its benefits GREATLY outweigh any negatives. And as a classroom tool, the students seem to enjoy it as well, as they can read real life reviews of potential books and resources. We are living in the Amazon age, where people base much of their shopping off of the reviews of others. Goodreads is no different in now that we can base our reading resources off of the review of a community of like minded readers. And what's also great about it, is once you set up an account, there are means of keeping track of what you've read and what you've reviewed. It's really just a great resource. I love Goodreads and it gets my highest recommendation!!!
How I Use It
This tool could be used in a number of ways for a class. I would think that primarilyy, it could be used as a research tool in order to the check the validity of sources and materials used in classroom work. In fact, the way that I used it, was just for that. I had students research a number of different art history books and determine what Goodread users thought of them and whether or not the books would be beneficial resources for our class. Students found it interesting to see real people reviewing the sources and found it more personal and helpful. Sometimes, it is an overwhelming task finding resources for assignments. Goodreads offers a means for prioritizing sources and even eliminating extraneous items that may be less than useful.