The Piano Teacher is a french movie. A very french movie. It's deep, intellectual and metaphorical. Haneke likes to create the most emotionally disturbing scenes with the absolute minimum of movement and dialogue.
Erika is a repressed, harsh and icy piano teacher teaching at a famous conservatory. She has no friends or lovers, lives with her demanding mother, and finds relief through various sadomachoistic practices. Walter, a gifted student, enters her life and her world of perverse sexuality that rejects seduction.
To understad the film, you definitely have to listen to the DVD commentary afterwards. I wouldn't recommend it unless you're really into disturbing arthouse films. It's certainly not erotica.