It isn't scary at all, you may jump and cringe a few times, but that is about it. It is really good though.
I can see where you're coming from. I felt like it was a fine line between boring and entertaining - brilliant either way however. I liked it, but I can see why you didn't. I didn't like the Wrestler. Felt like that was a close call too. It's like he gets great acting performances out of his stars to carry an almost boring story. At the end of the day it was just a move about ballet really, no matter how you sugar coat it.
Spoiler Pretty much starting with the sex scene with Lilly (Mila Kunis' character), almost everything to the end were for the most part hallucinations on Nina's (Natalie Portman) part. So, obviously she hallucinated seeing Lilly in the dressing room and the whole fight that ensued. She did the Black Swan dance based off adrenaline alone as well as the finale. When she jumped onto the mattress, Aronofsky left it ambiguous if she really died or not. At least that is how I interpreted it. I read a pretty interesting analysis on it in which the movie is basically the story about Nina's wrestling with her ego and id. Both her mother and Lilly play pivotal roles for her, psychologically.
Agreed although I would add that Aronofsky is an "abstract" director along the lines of Lynch and Kubrick. He makes movies for art sakes and as a result, he is one of those "love or hate him" directors.
I've always been a fan of Aronofsky's films so this on didn't surprise me. I do think Natalie Portman just did what she does....be the baddest actress on the planet.