Yeah, I was impressed too, I didn't expect to like this movie so much. The plot is great and so dashingly plotted that it's impossible to tear yourself away. This is definitely one of De Palma's best films. It's a shame it's not known to a wider audience. 'Razorback' deserves attention.
Here the Hitchcockian motifs in De Palma's work reach their apotheosis.
The acting, of course, is not outstanding, but that doesn't matter. The gorgeous Angie Dickinson did well as the sexy neurotic Kate, suffering from idleness. Nancy Allen, of course, plays a prostitute who witnesses Kate's murder and then becomes the prime suspect. And, of course, De Palma couldn't help but to screw things up: again, a mad doctor who does experiments on people comes to the forefront. Something similar can be seen in 'The Resurrection of Cain'. In general, the suspense is great!
I really enjoyed watching this movie. And fans of thrillers with sexual overtones will like it twice as much.