The documentary shows the artist rehearsing for a series of planned London concerts before he died June 25. His residency at the O2 arena was to have begun in July.
Although the film was not to be screened for the media until Tuesday night, MTV News said Taylor saw it last week and was told not to discuss it until Monday. As soon as she was allowed to, she posted several messages on Twitter praising the movie.
"It is the single most brilliant piece of filmmaking I have ever seen," Taylor Tweeted.
"It cements forever Michael's genius in every aspect of creativity," she added. "To say the man is a genius is an understatement. He cradles each note, coaxes the music to depths beyond reality ... I wept from pure joy at his God-given gift. There will never, ever be the likes of him again."
Taylor also complimented director Kenny Ortega for his work on the documentary.
"From A to Z you get Michael's input on every level," she said. "Michael's genius at work with the dancers. Mr. Ortega catches Michael in his every mood ... You see in front of your eyes Michael's genius blossoming on this piece of film thanks to Kenny Ortega and his crews. I truly believe this film should be nominated (for awards) in every category conceivable."