Frank Thomas considered her the best voice they ever had for an animated character.
Animator Milt Kahl stated that he probably had more fun animating Madame Medusa than any other assignment at Disney. While working on the film he was also amazed to find out that a lot of her dialogue was only recorded once. Milt had been looking for an outtake of a certain line, but there weren't any. Many of her first and only readings became production dialogue instantly.
Page had a strong instinct for who the character was and how eccentrically she should be played.
Milt said: "This actress was so good, she could make poorly written dialogue sound great!"
He watched some of her films to get an idea of her acting background, and he fond a particular acting moment useful for a scene he later animated.
In the 1962 movie "Sweet Bird of Youth" Page is acting opposite Paul Newman. At one point Newman tries to get to the telephone she is holding. To keep him from getting closer, she kicks him in the gut and pushes him away with her foot.
Medusa would repeat this moment when she tries to keep Penny away from the Teddy Bear, she grabbed earlier from the girl's arms. "Medusa kicks the little girl away with her boot, which is an awful thing to do and right in character," Milt explained.
A few years ago I had the he chance to listen to an old voice recording with Page as Medusa.
She started out by quietly asking the director a few questions, but then when it was time to record, she bursted her lines into the microphone as loud as she could, like: "PEEEEENNY DEAR, AUNTIE MEDUSA WANTS TO TALK TO YOUUUU!! Then very quietly to the director: "How was that?"
These are a few sketches Ken Anderson made while Geraldine Page was working on The Rescuers.
A pre-production design sketch by Milt Kahl, showing a sort of sensual quality.
To me this is the scariest drawing Milt did of Medusa. Her eyes, the way she points into camera, this woman means business.