I am re-reading The Host for the first time since i was a teenager, and i am struck strongly by Stephenie Meyers talent for writing harrowing horror stories, which she either consciously or subconsciously dresses up as another genre.
The world building is still fascinating, one of the most fascinating ones i read in a scifi book actually, and it is really better written than twilight because the plot is less batshit and she has more writing experience.
The movie, which i rewatched recently, is not even half as good as the book. It's a good movie and i really enjoy it, and a good adaptation. But the story is extremely reliant on internal stuff, and the details of the world building are lacking in the movie. I do think that a proper 24 episode tv show would have conveyed the story much better. With a slightly experimental structure because monster of the week doesn't work and it doesn't need multiple seasons, and with some creativity on how to do the world building and build both the current day plot and the backstory convincingly while staying true to the emotional impact of the plot development. Some expansion on how the early invasion happened, how the humans started to figure it out.
It also has less mormon bullshit than twilight, but i can't shake off the feeling that the souls are based on mormon mythology. Based on that feeling and her other work, i am basically certain that the horror aspect of them is not done on purpose beyond the repercussions on the humans. I think that Stephenie Meyers genuinely believes in the positive attributes of the souls they believe about themselves. And it influences the reader too, because the conclusion of the story is based on the truth of those attributes. I mostly believed them when i first read the book over a decade ago.
Which takes me back to my initial point: if Stephenie Meyers were a bit more aware of the horror aspect of the souls, and had highlighted that more in the book, then the awesome world building and compelling story would have reached their full potential. You wouldn't need to change the plot, just slight change in the way the story is told.