To begin with, the first six chapters are 2-4 pages long and each one introduces a new character. So the reader is hit all at once with a lot of information that is hard to process. Although the character sketches are interesting, it was a bit too much for me - it took me a while to get the characters straight after that. I kept on confusing details of the characters in subsequent chapters. I think the narrative would have helped if she had started out with one or two or even three characters, developed them a little, and then started adding in more characters.
Although I enjoyed many of the details in the book, I felt that there were parts that dragged a bit in the middle. There are certain story lines that I feel are overdeveloped - the reader really doesn't need to know the complete background of all six+ of the main characters. I felt by giving the reader too much, it slowed down the narrative at points.
I don't know if it's a trend, but I've read several books recently where a rape/forced or violent sex occurs unexpectedly, but nothing changes because of it. The character who is assaulted doesn't even think about prosecuting the man. He gets away with it - the story infers that this isn't the first time he's done it and probably isn't the last, since it's hinted earlier in the narrative that he's "mean." Maybe I'm reading too much into it, but I dislike this motif in a story line if it doesn't contribute to the plot - neither character involved in the assault changes significantly (or at all) because of it, so it's just a meaningless event that happens. Just my personal opinion, of course.
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Overall, I might recommend this book to people who already have an initial interest in ballroom or dance culture, but probably not to readers who aren't interested in that world. There are parts that are fascinating, and some good character sketches, but in the end I felt it fell a little flat for me.