The Mist. A book originally written by Stephen King turned big screen. Ever seen the trailer? (read more to view it) It looks fantastic.
When you start watching the movie it starts great. You get the plot.. small town, "natural desaster" and neighbour feuds. Even when the mist comes and 'takes' a life (be it in an unatural way) it's still great. Then, it falls downhill when you catch a glimpse (about 10 minutes of screen time actually) of what's in the mist. You still can bare to watch it and when you hit the ending.. all hell breaks loose and you want to do what the main character did to his new friends (read more to watch the ending spoiler), to yourself.
The trailer. The really, really good trailer.
The fucked up ending (yes, the ending. A spoiler).
Ignore the Toyota crap. It's still the ending, except he screams afterwards for about 5 minutes.