While Sisters is not his first overt nod to Hitchcock—that was Murder à la Mod (1968)—it is the best, and most mordantly funny, in a career that also includes the glosses Obsession (1976) and Dressed to Kill (1980).
Blurring the line between cheapo exploitation, arty experimentation, and outright Mad Magazine–style absurdity, Sisters offers an early, vivid glimpse of a young master coming into his own.
You could argue that he was still testing the waters, but "Sisters," for all its low-budget creakiness, feels fully formed — from its sly opening bit of misdirection to its adroit use of split-screen to its memorably churning Bernard Herrmann score. De Palma's choice of subject matter couldn't have been more appropriate: With this film he effectively conjoined himself to Hitchcock, announcing himself as a skillful mimic with a mischievous side all his own.
Though De Palma's own images can't rival Hitchcock's in shot-by-shot psychological power, the intricate multiple-perspective split-screen sequences of "Sisters" offer a dense and elaborate counterpoint that conjures a sense of psychological dislocation and information overload belonging to De Palma's own generation and times. De Palma's cinephilic devotion... is conflicted and cautionary—he sees movies as a source of hidden truths that risk becoming traps and delusions.
SISTERS is no insular work, pillaging all its best ideas from Hollywood's graying masters, but a living, beating, furious wasp's nest of a work, stable at a distance, but ready to explode with the slightest touch.
De Palma's obsessive use of doubles starts with the title (familial bonds, "right on!" feminism) and extends to the film itself with bifurcated frames, parallel montage (a birthday endearment scrawled letter by letter on a cake while the medicated heroine writhes on the bathroom floor) and, finally, the split-screen of a stabbed camera.