if you don't like musicals then there is no point. it takes a Broadway musical and stretches it out to two movies of music. the second part spends a lot of time wrapping up loose ends and making the plot match up with the canon Oz.
I know who she is because an ex dragged me to two (2) Kristin Chenowith symphony hall performances where she sang Wicked songs and other shit, I was possibly the only straight dude in the audience, hated it but she is a great performer, personality and singer.