I guess on a superficial level, there are some ethical issues - parents divided between what is best for one child vs. the other vs. the family as a whole - but the whole situation seemed implausible the whole time. What do you mean, they never thought to ask the second child what she felt? The story revolves around a lawsuit initiated by the younger child seeking medical emancipation, and as I said before, it was a little far-fetched. And I don't really see the ethical debate - in the case of an organ donation, it must be voluntary, and the best interests of the donor have to come ahead of the recipient. Or to put it more coarsely, if the donation goes ahead, the donor will likely face life-long restrictions to her health and activity level, and the recipient will probably die soon anyways due to the underlying condition. So since I didn't buy into the ethical debate, the book seemed rather shallow, and built on a flimsy foundation.
But having said that, it was a light, fluffy, holiday read that kept me reading until the end. But it too didn't make it back to Canada - I left it with a Tanzanian high school student who likes to read novels. I don't see it presenting any challenges to someone for whom English is her third language!