I've just finished it. I enjoyed it all the way through, and then WHAM, the last twenty pages or so left me feeling frustrated. The ending feels unfinished, rushed.
"The Poisonwood Bible" and "The Lacuna" left me with a similar dissatisfaction. I like her style of writing, but she seems to run out of steam at the end of her books. Am I the only one to feel this? I was expecting an epilogue in "Flight Behaviour" and was disappointed that there wasn't one.