I came to this story in the reverse order of my normal experience. Usually I listen to a book during my commute that I've found on a "greatest novels" list, and then watch the movie if one has been made. For this story, I watched the movie last year based on a Netflix recommendation and really liked it, then when I was looking through my lists for an "I" author (yes, I'm so anal that I pick my books alphabetical by author) I found this one. It was weird for me to listen to a book whose movie I'd already seen, but as usual the book had so much more detail that I was fine with that.
I really loved this book, due to the great development of the characters. I'm a sci-fi fan and anything to do with alternate histories or such is attractive, so the whole clone element was interesting to me. But the alternate history/clone part was actually just a backdrop to the real story, which was the relationship between the three main characters. The writing was so good that all of the experiences and feelings of the characters seemed so real. I grew up in a very conservative religious school, so the interactions of the kids and their feelings toward their "guardians" seemed familiar.
Overall, great writing, amazing story, and some of the best-developed characters I've ever read.