Not a bad movie, a lot of good performances. Not just from Joile but also Moss and Duval. But Ryder my God did she suck assss. shes been good in some movies like Beetle Juice or Edward Scissor Hands but she was a bad choice for this. She had three settings, looking bored, pouting or over acting to the point where it was actually hard to watch her. like that part where she is in the tub and yelling at Whoopi. just look at the faces she makes, its terrible. good movie other whys.
The reason Winona was in it was because she actually helped to produce it. (Check the credits.) As to why she chose this project, she was (supposedly) a real-life inmate at a similar facility, some years earlier. Remember when she was supposed to have done the 'daughter' role in Godfather 3, but then suddenly wasn't available? The 'official' story was 'exhaustion', but rumor has it was more 'mental'. I suppose it's understandable why you accuse her of 'over-acting' in that bathtub scene, but remember that the scene was meant to show us a 'borderline' personality acting out. Note the contrast between Winona's hysterics, and Whoopi's calm retort "And you're just throwing it all away".