There is a lot going on here... time travel, magical "affinities," good guy, bad guys, bad guys you thought were good guys...  The way the story started, I thought there would be a lot more time jumping, more action from the characters introduced in the first few chapters.  This isn't a complaint, necessarily, but the beginning of the book feels very different from the rest of the story.  Don't go into this thinking you are going to hear about all the "pilfering from the past" Esta does. That would be an awesome story on its own!
What we do get is an engrossing story about life in the early 1900's.  I like that Maxwell discusses how segregated the gangs of New York were at that time, based on where people emigrated from, down to what village they left.  Esta drops in and manipulates her way into a heist that could change the future for those that still have magic left in them.  The cast of character is large, but Maxwell makes it work.  I didn't lose interest in the story once, and MAY have stayed up too late a night or two to finish the book!  Check this out, it's definitely worth it!!