Catching Fire - what age is it suitable for?

The second book in the Hunger Games Trilogy - Catching Fire.  Our eldest daughter (age 11) read all three books recently, and then our youngest who is 9, picked up the first one from the school library and read that.  She really enjoyed it and launched into the second book straight afterwards.  Unfortunately she didn't get very far with the second book, saying it was boring.  Often when she says something is boring, it means it's too tricky, or she doesn't understand and she consequently gives up!
So - to encourage her to try again, we hired the first movie and all watched that together.  She enjoyed it and wants to see the second one but is still reluctant to read the second book. What I've done now is to start reading it with her. We take turns reading a chapter each day. We're only just at the beginning of the book, and it is quite slow to get going into the story.  There are also quite a few words that she's asking about the meaning of.  I think this is definitely the way to read this book. I enjoy reading with her, and it's good for her to practice her reading aloud as well.  With the incentive of the second movie to watch at the end of the book, that will keep her going until the book gets into it's 'groove' so to speak.
I tried to look up what age The Hunger Games series is recommended for, and most sites seem to say around 10 or 11 as the youngest age. At 9, I think our daughter is ready for this book and it is challenging for her.  However, I also think that reading it together with me is the best way for her to read it as she has plenty of questions to ask for each chapter, so I can help her understand the story more fully. I think having read the first book of the series, the content of the story isn't a problem for her. It's just the vocabulary and the tone of the book is just a little older than she is. It's always good to have an achievable challenge!
Have you or your kids read The Hunger Games?  

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