Whether you like the rest of the movie or not, the ending takes a steaming dump on everything. Textbook case of "we care more about shocking the audience with a twist ending than providing a satisfying ending that sensibly follows the events that came before it" syndrome - writers were clearly lazy. I don't say this just because the ending is 'unhappy,' there are lots of movies with unhappy endings that are incredibly well made. This, however, is just an insult to the intelligence of anyone who is unfortunate enough to watch it. An hour and a half of my life I'm never getting back. Save yourself the aggravation.