5 Stars if you have been reading all the Dark-hunter universe books. Lots of information (clues about the past and future/ things that have already been discussed and some that have not as of yet) that would be confusing or lost to the non-readers of the adult series. I give it a 5 solid stars and I am super excited for the future books. 
 4 stars if you are just reading this series and are unfamiliar with the adult universe.