Dated and overrated
The story is good but it's badly executed.
Maybe in 1970 it was classed as a brilliant movie but not any more. Some films like Psycho 1960 remain great no matter how many years pass. But not this movie.
There aren't enough twists and turns and the soundtrack (la la la la la...) kinda sucks.
It took me a while to finish watching the movie. Probably stopped and re-started it about 7 times.