This movie was excellent.
Pretty shocking that people think the acting here is terrible. It was across the board excellent. Portman deserves all the praise she's getting. Her performance was really affecting and carried the emotional weight of the film. Watching her descend from a sweet and naive girl into a psychotic self destructive force was very chilling and made complete sense since the film makes perfectly clear that she's been having such tendencies in the past, just on a much smaller scope. It was the best performance of her career by a huge margin. Cassel was also excellent, and Kunis was solid as well, though her role was the most straightforward by far.
Not sure what was pretentious about it. It is a melodrama, that's what it tried to be and that's exactly what it was. It was also pretty damn creepy.
Her acting in Brothers was competent but much shallower. She had to pretty much play two characters in Black Swan while still remaining grounded with enough nuance to not waver too far in one direction or the other and remain singular.
She has never done anything requiring the depth that was needed in Black Swan.