Man, Roman Polanski may have been a pedophile rapist, but he's made some amazing movies.
This is the most interesting take I've seen on Macbeth; it explores the whole self-fulfilling prophecy idea in a really clever way, and dips into psychological horror territory. The performances accentuate this, and the lead Macbeth in particular does a great job.
This movie blew my mind because it's the oldest one I've ever seen that relies heavily on handheld cameras. I had always thought that Freidkin's The Exorcist invented the style, but turns out it just popularized it. Polanski masterfully sets up 5, 10, or even 20 unique frames in single long takes instead of cutting, much like how Spielberg does. It makes for some very interesting blocking opportunities and real-time scenes.
Some of the scenes feel very modern, which is unsettling for an almost 50 year-old film with 400 year-old dialogue.