Finished watching it. I think it's a great movie! Here's my thoughts (slight spoiler warning):

I'll first start by talking about the positive aspects of Chou Kaguya Hime's story, which is the fact that the characters are connected with both the real world and the virtual world. I like the fact that they switch things up to keep it somewhat varied and grounded, like Iroha's problems in the real world and her more passionate side in the virtual world. She does have her own life, problems and desires. The discussions are also about things other than music, so that it's not "just" a musical anime. It has a fair bit of action too, which makes it more diverse. There is also the fireworks scene with Iroha and Kaguya, that manages to pull your heart strings a bit, which is nice.

Now when it comes to the negative side of the story, I have to mention that there is almost no sense of any realism. It's a constructed story, where money appears randomly despite Iroha losing her entire savings shortly after. Kaguya knows how to program things, but not how to play instruments, because if she is able to program and grow insanely quickly, then I will assume that she is a magical being that can do anything. Everything is prepared so quickly, hence my complaint.

There is not enough important screen time given to Kaguya to make her sentimental moments worth remembering. Her presence was short lived, which made the entire announcement of her departing from Earth appear somewhat meaningless. There are way too many time skips. How did Iroha become a scientist in a single week? It doesn't make sense, and the characters never truly struggle or feel the need to improve either. I can't give the story any higher than 7/10.

Animation style is excellent, but the choreography is corny at times. I absolutely do not like the dance choreography during the song concert with Iroha, Kaguya and Yachiyo. It's weird and almost makes me cringe.

The action choreography is at its best during the last fight. The animations are fluid, impressive, and the movements are badass.

Visuals are colorful in the virtual realm and dull in the real world, which is not a bad thing, but they aren't as clean as something like Bocchi the Rock!

Characters are diverse and their outfits are excellently designed, like Yachiyo's elegant and traditional Japanese clothing, for example.

Songs are wonderful! I personally don't like how frequently they play a new song after the previous one, but the songs are nice to listen to, which I guess is a compensation. I enjoyed the credits music, which is a remix of the song 「ray」 by Bump Of The Chicken.

Sound design-wise, it's immersive! The sound of the fireworks and the overall bass of the music hits perfectly. The intensity of the fireworks especially sounds quite close to an actual real-life one.

The pacing of the movie is too fast, which makes many of the scenes feel unearned and unrealistic.

Overall, I think it's an 8.5/10. The story and the choreography are not all bad, but they have their issues. I don't have anything negative to say towards the rest, except my little nitpick on song frequency.