I'll keep this short.
Laura and I saw The Mist on Wednesday night with about 50 other people at the Lowes. The first act is pretty slow and plot-devicey. It's all about getting everyone in that supermarket and showing the various character types that are going to butt heads in acts 2 & 3.
The movie is pretty good. The strongest visuals rely on the "seeing things, but not really seeing things" effect. But most of the goodness of the film stems from the last half hour or so. The special effects are pretty bad (the film had a 20 million budget. that's right -- 20 million. for everything.) Darabont does some nice things with the atmosphere and relies on the mist itself to make some of the stuff more scary. but when the effects need to be good, especially in an early scene, they are not good. in fact, they are Tuesday afternoon Sci-Fi channel bad.
Main character (name escapes me, as does the actor) is great. Good acting, interesting enough character. Everyone else is okay -- marginal performances, but better than any b-movie crap horror remake that gets vomited out recently.
Marcia Gay Harden who is stuck with a ridiculously poor set of speeches to work with. The only reason you don't laugh is because Harden is good enough to make you think twice about laughing. but then, eventually, you do laugh because her character is ridiculous. i don't care what anyone says. Just because Harden does a good job doesn't mean the character is ridiculous. she (the char, not harden) suffers from Nicholson-in-the-Shining-osis. Essentially, that she's crazy from moment 1, so you know she's not worth caring about in any sense. but she's also not complex in any way. You don't SEE her lose her mind. You just know she lost it at some point waaay back in her past. she's a joke to everyone and when she manages to get a bunch of people to listen to her, you're supposed to see her as a threat. but she's still a joke, as are the people who follow her (as evidenced by one particular shot of a character who switches sides -- it's funny when you see this particular character join her in prayer).
On to the more spoilerific responses and my thoughts on the ending for those of you with no interest in seeing the film or for those of you that already experienced the gut-wrenching film....