I really, really liked THE MIST and plan to buy it on DVD when it comes out. My sister also bought both herself and me the novella after we saw the film, so I am just now reading it. (Listening to the audio book of King's THE WASTE LANDS right now, too.)
I voted it an 8 on a scale of 10 at imdb.com.
The discussion here about its merits or mistakes, as well as the changes to the ending, are exactly what should happen with a film like this.
I thought the monsters were inventive, especially the large one. While the smaller flying ones did make me think of NIGHTWORLD, as it did for others here, I still think they were different from Paul's creatures enough in the context.
When the characters stop to stare at the large one, a thought coalesced within me that had been brewing for some time. More than a thought -- a deep feeling, and it was this: Nothing will ever be the same again. We, as a human race, will have to find a new way to survive and live that is dramatically different from what we currently know.
In that sense, even in the desperation of what they had seen, I retained some sense of hope for some reason. I will address that and how it relates to the ending below. But first, some spoiler space...
HERE THERE BE SPOILERS....BEWARE!!!!
I appreciate the ending in the film with its completely dire perspective and "if only" shock. But I feel I would have done something different if I were in the same circumstances. I would see how many bullets were left and say, "Well, let's do what we can, knowing that we have these four bullets to off ourselves (less one person) if it gets that desperate."
Of course, I have the luxury of evaluating what I would do from the vantage point of a seat of a movie theater. Would I really be that optimistic if I had gone through what they had gone through? Maybe we never know until we get there. I just tend to think that you should try everything you can until there is no option other than death. Regardless, I am sympathetic to the conflict within the characters that led to their choice. I view the film as sending a message of hope, actually, by showing the dire consequences of a wrong choice. The message I take from it is NEVER GIVE UP. You never know what might be right around the corner.
On a different topic, I really liked the fact that the explanation of where the creatures came from was NOT supernatural, just as Andre Braugher's character suspected. It was more frightening to me that it was the natural order in an alternate world that such creatures existed. Just as people can slip between the worlds held together by the nexus of The Dark Tower in King's other work (as I understand the series so far), the military had stumbled upon one of those portals. It was just as likely that Roland or the lobstrocities would have stumbled out. No such luck.