I finished this book yesterday on a return flight from Las Vegas, Nevada.
Let me start by saying that the only prior Libba Bray book I had read was A Great and Terrible Beauty, which I liked, but didn't love. I liked it enough that I bought the sequels, but I didn't love it so much that I actually read them, although I still intend to do so someday. This book may inspire me to give that series another go.
The Diviners is an ambitious book - it is very long for a YA and it has a lot of moving parts. There were aspects of the book that I thought were very successful, some that I found a little bit awkward, and some that I didn't really like all that much.
What I didn't like: I really grew to hate the flapper-speak. I am sure that people sprinkled their daily speech with flapper-isms, but I felt like the constant "pos-i-tute-lys" and "baby vamps" and the like were distracting. I think that Bray was making a point about how shallow Evie was at the beginning of the book, and her growth as a character, because she did seem to use less of the over-the-top speech as the book wore on and she grew up a bit. Which brings me to the next point. Unfortunately, Evie just isn't a very likeable character. Perhaps this will change as the series continues - and I will definitely read the follow-ups because I liked the story a lot. Evie reminds me a bit of the main character from KMM's Fever series, who is all pink glitter in the first book and ultimately grows up into a superbadass warrior woman. If I were deciding whether to continue the series based upon my affection for Evie, it'd be a no go. She is annoying, self-centered, shallow, and reckless. One of those character traits in a heroine is good - keeps her from being a Mary Sue. All of them make for a MC who is sort of a pain in the ass.
However, what I liked way outweighs what I didn't like. I loved the setting overall. I loved Jericho, and the tiny clockwork elements that Bray added to the story (a bit of steampunk for the steampunk lover in us all). I loved, loved, loved, the ghost aspect of the book. I thought that Bray did an excellent job picking up the disturbing threads of historical American evangalism, spiritualism, and cult behavior, and using religious zealotry as a basis for her story. This is a uniquely American story and relied very little on European historical and religious traditions. This aspect of the book was well-excecuted and fascinating.
I really liked the romantic elements as well. She skirted a love triangle, but ultimately, I felt that she treated the romances in the books in a way that was very realistic, and appropriate for a young adult book. There was no sense of obsessive-love-at-first-glance, and she focused on developing friendships, connections and relationships between her characters first, and allowed the romances to develop in a much more organic fashion. She also broached the topic of interracial attraction/romance in a way that I thought was also very period-appropriate and compelling.
The ending was satisfying - there was a resolution to the primary conflict, but hints of a far bigger story to tell.
This book is well-researched. Bray's writing is workmanlike - she doesn't put words together as gorgeously as a writer like Maggie Stiefvater, but she writes a strong story, and this was a really strong first entry in a series that I expect to really like as it continues.