If you're looking for archetypal thriller / horror, this is not a great example of those genres. It is much more cerebral and thought provoking than those tags describe.
However, it is a long, long exploration of time, ageing, and regret that could've been done in half the time and much more succinctly - as if it was elongated for the hell of it.
The themes and ideas are great, but its translation from kaufman's mind onto film leads to an overly long, glacial-paced piece of cinema thats not engaging to sit through. There's no "ah-ha!" moment to tie it all together, no twist or final knowledge to put things in perspective. Just a lot of the same confusing scenes until it eventually peters out and... ends.
What the film is trying to do could have been done much more efficiently and fluently without giving itself away while still maintaining an air of the mysterious, and we know Kaufman could've done this, but instead opts to purposefully confuse.
Save yourself the time and just watch the farmhouse scenes, and 10 mins of car ride on either side.