There's ambiguous endings, and then there are movies that just stop. I'd describe the end of "No Country for Old Men" as deliberately ambiguous. (See my related post.)

One of my all-time favorite movies is "Blade Runner," but I do not have a copy on video because currently the only version available is the director's cut, which I despise. In that cut, they two main characters walk into an elevator, it closes and it goes black. That's a movie just stopping.

"The Squid and the Whale," while otherwise a fine film, also has an ending that I regard as unsatisfying.

People complain about pat endings, but the truth is endings are hard to write. I have more respect for a filmmaker who supplies an ending that's unsurprising than one who seems to have just thrown up their hands.

My opinion is that movies don't have to end with a finite resolution where all the questions are answered. But it has to leave the protagonist(s) in some way changed. We don't need to know the destination of where they'll end up, but we at least need to see the first few steps of their journey.

That make any sense?

I like a little ambiguity sometimes to keep us thinking, but as Chris said, it does usually show when you just don't know how to end as opposed to that being the plan.

I would have LOVED "The Mist" if they'd ended it about five minutes earlier than they did (or, heck, even three minutes earlier)--see http://www.indy.com/posts/1964.

But still there are those people who want everything gift-wrapped all the time. I do agree that the story needs to be finished even if the "ending" is vague. The threads and themes need to be completed before a movie is over.

People bring different expectations to different genres. "The Mist" has Stephen King's name on it, so people think of it as a horror film. And those are famous for their ambiguous endings. Although it's usually confined to, "How is the killer not dead after being shot 17 times? And will there be a part IX?"

So I would have been fine with "Mist" ending a little, well, mistily...

Another Ryan Gosling film, Half Nelson. There's a scene where the teen Gosling's character has become close to shows up at a motel room to deliver his drugs without knowing it would be him. No dialogue between the two. The entire scene is communicated with looks...and you have to guess what they must be thinking. The ending of this movie is equally ambiguous, but that one scene is SO riveting, probably due in part to the viewer analyzing the situation.