Dustin Hoffman does not play two characters in this film, but plays one man Micheal Dorsey an actor who pretends to be a woman Dorothy Michaels to get an acting job on a soap opera. He first is the struggling actor Micheal who works hard on his art, but perhaps is a little too difficult about it preventing him from getting work as an actor. Hoffman is very energetic, and although the role as the actor may not exactly be a challenge for Hoffman he excels especially well deriving the right amount of humor and charm in his performance.
Hoffman though really does shine as Dorothy though in an incredible performance. Although the viewer is obviously instantly in on the fact that it is Hoffman as the women, but Hoffman is fully believable anyways. His voice, is just perfect with his southern accent, and the way he changes the way he walks, and stands is all brilliantly handled by Hoffman. I never had a doubt that any of the characters would at all believe him to be a woman. This actually is a fairly a big challenge since after all he actually does not wear that much to look like a woman, but Hoffman due to the way he carries himself as a woman both physically and through his voice Dorothy Micheals is simply a perfectly convincing woman.
Hoffman though performance is not only a technical achievement though but is a thoroughly entertaining performance. In just about every scene he finds the right humor with Dorothy, and Micheal, in the double life. Hoffman is clearly working with a funny script but his timing is exceptionally good in this role. The jokes many of them are technically obvious jokes for the situation he is in, but the film and Hoffman really get the most out of them. He is simply hilarious with this performance, that is just a delight to watch. Comedy is always hard to describe why it is funny without over description, so I will just say that what Hoffman does is funny, every situation Dorothy/Micheal get into Hoffman does his best to make them funny, which he succeeds with incredibly well.
The performance actually always stays funny which is something I like but that does not mean his performance is at all simply. He shows a transformation in turning into a better man as Micheal by being a woman, which is strange but well incredibly well handled by Hoffman making it very natural and not at all forced of a transition for the character. Hoffman naturalism in this bizarre role is actually what makes every odd moment in the movie, somehow authentic and funny as well. I would say this is especially true about his "romantic" moments with Jessica Lange and Charles Durning. These scenes are over the top situations technically, but Hoffman makes them somehow play realistically and of course humorously, which is an amazing achievement since the scenes really could have gone all wrong, but instead they go all right.
I would say his best single moment is the reveal scene in the soap opera. This alone shows the brilliance of Hoffman's performance. This scene is both incredibly funny but also has the sentimental ending to his speech which Hoffman portrays wonderfully without taking away the humor from the scene nor does he make that part of the speech at all forced. This scene is just like Hoffman's performance mixing his performance as the man and the woman brilliantly and hilariously but also with the little more to the performance. Simply a great performance from Hoffman.
