The Girl on the Train

God, what a depressing book. None of the characters are likeable, I couldn't find myself caring about anyone and the end was just... nothing.
I really can't see why this has been the hit it has been - maybe I'm missing something?
The central character isn't redeemed, her flaws aren't overcome, she doesn't make a discovery through intelligence, just by, well, I don't want to give it away.
It's dull. That's the best I can say about it.