This movie is NOT about her singing

I was impressed by the courage showed by this movie.
It doesn't play by the standard biopic rules, infact it's not a biopic but a drama about downfall and love. If you want a typical biopic, check out the tv movie: this one dares to be a film on its own merits, and a downer, thus giving us a lasting impression of the tragedy of Judy's real life behind the galmour.

So, I'm fine with having the actress sing the song, without Judy's voice lipsynched, because the movie is not really about that. It's not just a showcase of "how great she was" or "what a great voice". Rather, it's about how her life turned out by owning that talent.

Zellweger interpreted the songs quite beautifully, and she was acting her role during those performances, so in this film I'd rather have that than the original voice, since this film is about the drama of the terminal year of her life: again, they had the courage to focus on that, and I think it pays off excellently.

Great movie.