According to the website:
Whichbook gives readers an enjoyable and intuitive way to find books to match their mood.
Instead of starting from the overwhelming choice of books available, whichbook starts from the reader and enables each individual to build theelements of that elusive 'good read' we are all looking for but don't quiteknow how to define.
The standard way of organizing books for choice, on shelves in a library or a bookshop, or on the web, starts from the products available - the authors,titles, publishers or genres. Whichbook enables, for the first time, the choiceof book to start from the individual reader and what they are looking for.
This site looks like fun. I am going to try it with my students.