Although I have not read the first two books in the series (Lucky and Gorgeous) I'm completely sucked in. While this is the third book in the series, Brilliant stands quite well on its own and a reader who has not read the previous books will have no problem getting into the story. In fact, I like the protagonist Quinn so much, it's hard for me to imagine reading the other two books in the points of view of her younger sisters. I'll be curious to read them and see how they compare and how they handle Quinn's character when she's not the central focus.
I think the thing that allowed this book to make such an impression on me is how similar I find Quinn is to myself. Sure, I've read plenty of books where I identified with the protagonist. In fact, one could argue that a strong protagonist has some quality, some essence, that the reader sees reflected in themselves and that is what allows us to sympathize with the character. But this is different. Quinn is so similar to how I was in high school, down to the way she gets along with her sisters and her propensity for academic achievement. It's like if someone asked me "if you were a character from a novel, who would you be?" I'd want to answer "Elizabeth Bennet" but really, the truth is it's more like Quinn Avery.
What about you? Do you have a fictional-character twin?