It would be very difficult to provide a simple review of Black Swan. It's a good movie, but it's very complicated and a little disturbing. It's not a happy movie - movies don't need to be happy - and it may not be necessary for everyone to see it.
Natalie Portman deserves every accolade being thrown at her for playing the prima ballerina and Mila Kunis deserves more than a few for playing the understudy. Great performances from the entire cast, actually.
But something bothers me about Black Swan. And that thing is director Darren Aronofsky. Lets take a look at Aronofsky's resume:
Pi (1999) A math genius goes insane trying to find God in the non-repeating digits of pi.
The Fountain (2006) A guy with a spaceship goes insane and believes that his wife had been reincarnated as a tree.
The Wrestler (2009) A self-destructive guy does self-destructive things for 105 minutes.
Black Swan (2010) A driven ballerina goes insane when she gets her dream role and meets her polar opposite the same day.
Notice a trend? Crazy people (some certifiably, others hyperbolically) doing crazy things. Aronofsky's movies are dark and disturbing. Some are good (Pi), some are among the worst movies ever made (The Fountain). I'm not going to categorize Black Swan. It tells an amazing story but it's very difficult to watch. I assume that's what he was going for, so that's good, but it was difficult to watch. Not sure what else to say.