It's strange to give such a low rating to a story with so many promising elements. The world building was rich and detailed, and the primary Jeckyl/Hyde character of Eliza/Lizzie was absolutely fascinating. Eliza was the scientific, steady one while Lizzie was the passionate, devil-may-care type, and either of them could have been a wonderful protagonist in her own right, and watching them attempt to come to some sort of understanding was a treat to read.
My frustration with this book was that Eliza/Lizzie was an amazing character who was utterly wasted. The woman/women were supposed to be inordinately clever, and yet were outsmarted and outmatched at every turn. Every major clue is basically handed to her by one of the male characters, all of whom seemed to be deceiving her and she was constantly in a state of surprise by this. She never really figured anything out until it was too late or until it was handed to her on a silver platter. I never really felt that she "bested" anyone. I don't want to have a protagonist made up to be a strong, female character, and then have her either need the aid of (or to be rescued by) her male counterparts, much less have her seem to be constantly duped. And the author spends so much time desperately throwing red herrings and false accusations into the mix that I was able to guess who the culprit was simply because this individual was the only one who DIDN'T have suspicion thrown their way.
This could have been one of the best books that I'd read in a while, but the author just didn't do the story any justice with her remarkable main character.