The site now has a place for book reports (I call mine book reports, they don't deserve to be called 'reviews'). 

Click on 'Books' in the Main Menu.  I had to look around for a while to find everything I needed. 'New Entry' is up near the top on the left, click on that to enter a new book.  You can also add your comments to any book report someone else has made, and vote on the book using a 1 to five stars vote.