I rate the books with one to five stars; actually two to five, because I would never finish reading a book that was so bad I'd give it only one.
** means it was just good enough to finish, or I had to read it for some reason.
*** means if you like that author or genre you'll probably enjoy it.
****means it is a very good book of its type.
*****means it is so good it transcends its genre; I think even people who don't usually like that type of thing would like it.