I've had the pleasure of watching Wicked the Musical on Broadway and other venues a few times now. I've also read the book. I was skeptical going into a lengthy show for just the first part but my family and I were blown away. The powerhouse vocals of Cynthia Erivo and Ariana Grande carry the film along with amazing acting from the entire cast. The cinematography is flawless in each scene - Emerald City was dazzling. The length of the film was justified as it provided enough time to fully develop the characters and didn't feel rushed, which in hindsight was a shortcoming of the musical. Bravo to the filmmakers for splitting the film in two and staying true to (most) of the book. I just hope Part 2 can live up to the caliber set by Part 1. We went to a small theatre and it was like being in a concert hall with the audience applauding at the end of each song. My son (six) who has also seen the musical, watched the Wizard of Oz, sat through the entire movie, and enjoyed it as well. I would be shocked if this movie doesn't sweep every Oscar category next year.
TLDR: A well-made film in every sense of the word. Just do yourself a favor: grab your bestie, and watch it.