The film leaves me somewhat undecided about it's merits. Films are generally supposed to be enjoyable affairs that allow the viewer to escape reality for a short-time, to be entertained and perhaps find some solace with the characters. If this is the case then Black Swan really does not merit it's placing anywhere near the Top100.
On the technical side however this film is possibly one of the best movies ever made. It is incredibly uncomfortable watching someone have a breakdown in front of you in the space of two hours. Even on second viewing when you know what is going to happen there were times where not only did I avert my eyes but I actually left the room. This film is so powerful that it has to be including in this list.
Portman to me is fantastic in the role. Her portrayal of the character is so believable that it is hard to remember at times that she is acting. From the timid and vapid character to begin with to the dauntless alter-ego of the black swan everything about her role is so beautifully created.
This is not a movie I think I could watch a third time, but is certainly a movie you have to watch once, and maybe if you are brave a second time.