Oscar nomination for Black Swan is absolutely necessary! (Spoilers)
Yes, he was manipulative and sleazy, but not a villian - just complex. Like any great teacher, he got results, and in the most crucial of moments, when he and Nina are together, alone, knew precisely what to say to get what was needed out of her.
Apart from that, Cassel's psychical presence on screen was a force to be reckoned with. His mannerisms and confidence were simply electrifying. I also thought it was wonderfully fitting toward the end when the power is shifted from him to Nina through a kiss, right after she's left the audience awestruck. Personally, their relationship together is the heart of the film, and what I found most thrilling and provocative. If the academy awards are smart, they nominate him, as well as Portman, who's obviously a shoe-in. I just think her performance wouldn't have worked as well without him.
Agree? Or am I over-hyping this?