Recently caught this one and really loved it. As my first run-in with early De Palma outside of Carrie, and despite how much it blatantly copied a lot of Hitchcock's techniques, I really dug it a lot. Gave me that Hitchcock fix I've been missing from his later years.
Been having a bit of a dilemma with category placement though on the two leads (or supports?) - Margot Kidder and Jennifer Salt. I absolutely loved Jennifer Salt in this and she has a good shot at being my winner by the time I finish up the year, but hard to tell whether the two females are lead or supporting. As of now I consider them Lead because they basically split the story 50/50 and then meet in the end so almost equal screen time (as opposed to Psycho where it's Janet Leigh's story until it's very obviously not so easy for me to place her Supporting - I only mention this since it's the only other example I can think of).
So figured I'd make it easier on myself and see what the majority thinks here.