Gwyneth is the perfect murder target

I love this movie. It really works almost perfectly.
The only mistake is the final duel's outcome, because everybody at that point is rooting for Douglas.

It works because Gwyneth is fittingly cast as a very murderable target:
she's a spoiled, selfish, lying, lazy daddy's little princess who has become a bored, boring, annoying, cheating wife with glaring daddy's issues. Plus a truckload of money if she dies.
And so is Emily.

So it's such a tease to end the film unfinished.