A lot of what makes this prologue so compelling is evidently Jupiter: The work they're willing to put into making their fans happy and alleviate the burden of the staff that help them. Them striving to prove that they have worth and can make it on their own is a solid method of utilizing the goodwill they have garnered because of the aftermath surrounding 961 in the original anime and builds a solid base for Side M, considering they'll probably play a prominent role in that show.
The interview scene is the strongest example of characterization featured in this 30 minute episode: their posture, their body language, their way of talking, it all feeds into what each of the trio's charm points are. The way the scene ended was a pretty great treat too, it conveyed how close they are in an incredibly adorable way.
The scene where they ran into Haruka felt very much like the passing of the torch. We see that not only was it an essential moment for her to get her motivation back, but it also pushed Jupiter to realize that they can't please all their fans the way they were, they had to aim higher. Both parties putting their past conflicts aside and genuinely hoping for each other's success while a piano rendition of the first iDOLM@STER opening played was not only an incredibly touching moment, but also the last step the viewer took, alongside Jupiter, to get past the threshold into the world of Side M.
The performance scene is the most worrying part. They managed to hide the parts where they had to use CGI models of the characters well enough, but the quality of the animation isn't nearly as good as in previous installments, which isn't reassuring considering the animation of the tv anime will probably be of lesser quality than what was shown. That said, it was still a pretty fun scene.
The prologue has everything it needs to get the fans of the series excited and hopefully the full show will be just as entertaining to watch as this was.
