Its very good. Its a low budget indie film. Its about two unremarkable engineers who work on toy projects in their garage accidentally discovering a type of time travel similar to the movie Looper. The film follows the realization, experimentation and ultimately the downfall of the engineers due to the power of their own discovery.
Primer is famous for being extremely complex and hard to follow. The characters speak in real engineering jargon, and there’s constant time travel paradoxes happening in the background which you don’t pick up on without multiple viewings.
If you like being intellectually challenged, its great.
Should also be mentioned that the director is a massive POS, which is why I don’t promote the movie even though I like it.