****Big spoiler******

Rating: 6/10 (18 October 2014)

I was fully engrossed in the film right up until about 30 minutes before the end but felt cheated by the end. I hadn't read the book, but when I came home and researched a bit more, I discovered that the writer liked the ending of Rosemary's Baby so that's why she chose her ending.
So here's the thing: I too liked Rosemary's Baby. I found the end credible because it was a mothers love for a child, and she pretended to herself that as the child was 50% her perhaps the baby would be OK. The Gone Girl ending just didn't work.
I can think of how I could have found it more credible. Say Nick had mumps recently and was now sterile, Amy used his frozen sperm to impregnate herself, so it was the only chance he would ever have to get a son. And the film should have shown him talking to his sister, describing how he desperately wanted a child but Amy didn't.
We shouldn't have seen Amy's version where she said she wanted a child but Nick replied that having a baby wouldn't fix the marriage. Yes it was from her diary but the visual impact meant that was how I viewed Nick. I was left feeling why did he stay? He said a marriage can't be saved by a child.
There, I fixed the ending!