I think the adaptation is better than the novella, mainly because of the ending. Probably one of the most affecting movie endings I've ever seen, also the reveal of thatwas astonishing.giant monster
I hated it because it robbed the story of its ambiguity. The novella leaves the following unaddressed:
What happened to the protag's wife (a down tree blocks them from getting to her); what happened to the woman who left the store early on, once the mist shows up (she's with the military at the end), and, worst of all, whether the mist took over the world, or will ever leave. In the book they never get out and don't know where the end is. In the film it's shown dissipating as the army rolls in. They also amplify the explanation of how the mist came to be, from rumors to a character spelling it out.
In robbing the film of of the open-ended nature of the story, they also robbed it of one of the main reasons I loved it. Not everything needs a bow put on it.
At any rate, I just watched The Void, which I wrote about in the thread. Clearly falls into the cosmic horror space, though the execution of the story is pretty poor. It did make me want to go back and re-watch From Beyond, though.