I saw The Quiet Earth in the theater when it came out, and I’ve always been disappointed in it. The biggest reason is that it had that spectacular poster:
This also turns out to be the very last scene in the movie. So, after showing you this poster that promises that this is what the film will be about, you finally learn that it’s not about this at all. (It’s a bit like the 2001 posters that show the StarChild, except that not ALL the 2001 posters showed that. and 2001 did deliver on the promised effects.)
The movie also., as TV Tropes points out, was supposed to be about The Last Man on Earth, at least at the beginning*, but the trailers spoiled that.
*movies purport to like Last Man on Earth (or wherever) movies, but almost invariably bring in other characters. They can’t help themselves. Even Robinson Crusoe on Mars had a Friday.