To sum it up: it's a compressed version of the first season. It does however, have minor new scenes. Emphasis on minor. And it's only two. I'll go through what they are at the end of this review because it's a slight spoiler from the first season.
I definitely recommend you watch this if you want a fresh up on what happened in the first season before watching the second season. But I do NOT recommend to watch this if you haven't watched the first season. It skips out on a lot of details that was in the first season and it'll ruin the experience for sure. So if you are here because you'd rather watch a compressed version of the first season rather than going through the 13 episodes.... hear me out and just give it a chance. Trust me when I say you will not regret it. (The animation/visuals in it are SO stunning).
Minor spoilers ahead (is this even considered a spoiler tbh?)
The added scenes were:
1) They extended the scenes in the Sunrise festival, which was nice.
2) They added a scene of Yuuko Yoshikawa and Mizore Yoroizuka interacting, which was NOT included in the first season. Glad they added it in though because it followed up within the second season and now things make more sense.
As far as recap movies go, this is a solid 7/10. Good enough for a review of the first season, but not good enough on it's own. First time writing a review btw, so I hope it was helpful!