Following along in my great tradition of reading the trendiest books long after their trend is over, I finally got around to spending time with Nick and Amy Dunne. I was completely unspoiled, having paid no attention whatsoever to reviews of either the movie or the book.
Well, in a nutshell, I didn't mind it - it was cleverly done - but I wasn't particularly blown away. At first I found the style (especially the Amy-diary style) irritating, but then I realized that it was deliberate and under control. The fact that there was a twist mid-book came as no surprise whatsoever, and in fact the only (mild) surprise I felt was that the unreliable narrator-twist wasn't played one more time before the end (i.e. I was completely prepared to discover that Nick had engineered the whole thing, including the manufacture of supporting documents and a "suicide" by Amy).
I fully understand why some people found the ending irritating, but that's just a variation on the trope of "evil didn't die" that shows up at the end of horror films like "Carrie", I think. It's your last, parting shudder (it walks amongst us still). With two such horrible people as protagonists, you're not going to get a morally satisfying ending short of tossing them both off a cliff - which, frankly, I would have been delighted to do at several points during the proceedings.
Oh well. It's always worth making a bit of effort to pull oneself further inside the circle of common cultural references. It felt a bit like a much-procrastinated duty, but as duties go, it was not a particularly unpleasant one.