The history and failure of this movie is pretty well known, but if you remove the Halloween title and just call it Season of the Witch, you can look at it in a different light. H3 is a cheesy b-movie with some nifty practical effects, a decent twist ending, and some decent performances by veteran character actors.
I know this is only produced by Carpenter, but there is enough Carpenter-esque moments, including archetypes that would appear in future movies, that it feels like he was deeply involved. This watches like a mix of Prince of Darkness and They Live. Still it is a guilty pleasure if only to watch Tom Atkins play the hero that he would perfect in Night of the Creeps.