Anyone who reads the book or is familiar with the story arc of her character, Hannah, knows that this is a juicy role that a talented actress like Kate can turn into a classic. I am very happy that I will get to see this film sooner rather than later. But I do not see how Kate can be legitimately a supporting actor in either this film or Revolutionary Road (another juicy part). Of course whether a performance is legitimately supporting or leading has little to do with how the studio promotes the performance.
Between the two roles (at least as presented in the books), The Reader's Hannah is far more suitable as a supporting role than RR's April. Leo's character, Frank, could have as much if not more screen time than April. But I see April as the protagonist of all of the major events in the book.
It can be argued that The Reader is actually Michael's story. He has his affair with Hannah, falls in love with her, then they are separated for a long time. Michael goes on with his life and when they run across each other again Michael learns a terrible secret from Hannah's past which affects him deeply.
The great thing in the world is not so much where we stand, as in what direction we are moving. It's faith in something and enthusiasm for something that makes a life worth living. Oliver Wendell Holmes