What are some of the best and/or worst adaptations?
Here's a couple:
Best
From Campbell's novella "Who Goes There?"
The Thing (From Another World) (1951) - terrible adaptation, wonderful movie
The Thing (1982) - reasonable adaptation, great movie
Worst
From Asimov's short story "Nightfall"
Nightfall (1988) - Asimov's hard to adapt to begin with since he tends to tell his stories primarily through dialogue, but this thing is not only an awful adaptation, it's also a fantastically bad movie.