@Jared - perfect response thanks, exactly the sort of stuff I can make use of. Looking at the logs you displayed:
Could not find title/authors/goodreads id for u'http://www.goodreads.com/book/show/12904336-sisterhood-of-dune'
Goodreads: u'12904336' Title: 'Sisterhood of Dune' Authors: None
There is logic in the plugin that says if it can't find *all* of a goodreads id, title and authors as the result of scraping a web page then it aborts returning any results, displaying that first error line. The line underneath displays what it did manage to find - which as you can see is that while it got the goodreads id and title, it did not manage to detect the authors for that book.
Now it could well be that Goodreads have made a small change to their web page which is causing that issue. It is interesting that when I tried it last night I did not have that problem, though it could be like other websites have done in the past that the new website changes had not yet been globally rolled out and we were hitting web servers delivering different versions of the page.
Probably won't have time to look at this tonight but certainly will tomorrow night - thanks for the details, it greatly helps.