**** SPOILER ALERT *****
I worked on this show for some time a few years ago. I have a few definite suggestions.
The first act is fine; the second needs definite pruning, starting with the unnecessary love duet "Chick-a-Pen", which is like bad early Disney and makes proposed spousal abuse seem cute.
Something needs to be done with the stupid '50s-style ending which solves nothing and is historically inaccurate, sexist, and laughable. Some sort of believable truce between Molly and Johnny, instead of her giving up everything to go live in a cabin in the woods (which the real Molly did not do--and, honestly, who would?) The movie actually is an improvement in this sense, with a restrained ending recalling "My Fair Lady."
The actress who plays Molly must have a large and distinctive personality AND YET BE UTTERLY CHARMING. She does dislikable things throughout the second act; she must be bewitching enough to make the audience forgive her for them. Carol Burnett or Dolly Parton in their prime could have pulled it off. I can't think of anyone else offhand--didn't I hear that Reba McEntire was thinking about it? She could be perfect.
I ask in all honesty/What would life be?/Without a song and a dance, what are we?/So I say "Thank you for the music/For giving it to me."