*Almost* 5 stars for me - detracting half a point for the challengingly slow start (really had to force myself to read on), and the overused "pack mentality" trope that so often plagues supernatural romance.
That said, the book is a delightful read: it engages your knowledge of history and science as the characters talk about books and their authors, and it was just really enjoyable to come across so many references I know from completely different contexts. Plus, the deliciously slow build-up on the romance created a suspenseful story arc! 

There is a lot of character establishment and world building here, so I feel like Books 2 and 3 of the series will give a more rounded picture of the actual character development - for this book, there are places where characters seem a little predictable, and Diana doesn't feel like she's fully come into herself. 

<spoiler>I was a little unhappy that the first book basically builds up the actual start of the adventure (think Fellowship of the Ring), and the final bits are leaving you in the most annoyingly delicious cliffhanger. Have already ordered the other two books, but will have to wait a couple days for them to arrive... can't wait to dive in!</spoiler>

Overall, a strong recommendation for any history buffs looking for supernatural romance.