At the moment the data comes from amazon but I'm just about to add a module that takes review data from goodreads. To answer your 2nd and 3rd questions; it cam

At the moment the data comes from amazon but I'm just about to add a module that takes review data from goodreads. To answer your 2nd and 3rd questions; it came out of a requirement I had to be able to quickly segment/categorise books I might want for myself but I think other people also use it for gift inspiration. I found gender was a reasonably neat line for me to be able to segment. I've also found it a little more-ish to check up on books I've read in the past and see where it lie on the spectrum. This is not supposed to be a one size fits all in book categorisation and segmentation - it's just another tool. Some people seem to have fun doing it and find it useful - some are even clicking through to amazon to purchase.