I never really thought of it as science fiction (see her MaddAdam series for something more SF-y), but I love the book and think it does a great job of extrapolating from various political trends into where parts of the "western world" could end up going.
I'm also not surprised it's a candidate for being banned, either from people who think it paints religion or conservativsm in a negative light, or people who think it might make anyone under 18 uncomfortable. Is it appropriate for 5 year olds? Probably not. 16 year olds? Seems reasonable to me.