I just saw Wicked and I was shocked by how good it was! At first, I didn't want to watch it because I saw Ariana Grande was casted as Galinda. I thought it was just a dumb celebrity casting and she would just sing in pop style. But I kept hearing good things about the movie, so I decided to go see it. VERY glad I did!! The costumes were absolutely phenomenal, and the singing was quite good. I particularly liked the Elphaba actress. Her belting sounded very effortless and healthy. And I actually really liked Ariana as Galinda. I forgot it was her, and I just saw the character. She adapted to the musical theater style quite well, and even sounded operatic on those high notes.
The costuming was honestly better than what I've seen in many a period drama. I think Galinda and Elphaba wore corsets, given that their silhouettes looked nice and snatched, and their fitted jackets and dresses fit very smoothly on them, not wrinkling or moving around. They looked like they were clinging to something solid. There were also many sources of historical inspiration in the costuming. For example, Elphaba's gorgeous overcoat in the beginning, with the corded embroidery and amazing puffed sleeves, looked very 1890s to me. I also saw characters with authentic 1920s fingerwave hairstyles. I've seen some 1920s period dramas where they don't do proper fingerwave hairstyles. And in general, I just wanted everything in Galinda's wardrobe.
Now, I had never seen Wicked on Broadway or anything, so I wasn't that familiar with the show. But I watched it with a musical theater friend, and I asked her afterwards how accurate it was to the show. She told me it was very accurate and they only made a few minor changes here and there. But otherwise the dialogue, song order and everything was exactly right.
I'm very glad I didn't allow my preconceived judgment about the actress to get in the way of my enjoyment of the movie. I finally feel like we have an actual good movie version of a Broadway musical. It seems like the Wicked movie actually understands what Broadway fans want in a movie: we want to see the show as it's written, with good quality vocals, though maybe with some slight creative changes in the scenes since a movie format is more flexible than a live stage performance. Neither the 2004 Phantom movie nor the 2012 Les Mis movie deliver on this, unfortunately. The Phantom movie vocals are an atrocity and make my ears bleed. The Les Mis movie had beautiful and heartfelt acting, but the vocals were poor (with the exception of Samantha Barks as Eponine, and Aaron Tveit as Enjolras, and they're both Broadway people). And yes, all that is my opinion. But my opinion is backed up with knowledge I've learned from taking classical voice lessons.
But anyway, in my opinion as a seamstress and soprano, Wicked was amazing and you should go see it!