I played this game on stream: https://www.twitch.tv/videos/2560917305?t=01h02m51s
Overall, the graphics were really nice, and I liked that there were mini-games. I found some of the minigames somewhat hard to play in terms of the controls/UI. I was also disappointed that the demo stopped before the first trial/challenge, because that would have been great to experience.
Each idol had various stats like singing, dancing etc, but I couldn't really tell exactly what each stat is for, or if I should get everything high for everyone, or have different people specialize in different stats. The training also seemed to be for the whole team, so I don't know if I could even have different specialities. I think having different stats is good but there should be some way to understand what they affect.
I was also disappointed that the demo ended before the first trial/challenge, because I was hoping that that would give me a better sense of what the stats do..
The mini-games were overall nice, but there was a few where I didn't feel like the controls/UI was good and I couldn't really play the mini-game properly. One was the auditions, and there might be another but I don't quite remember which one (you can check the VOD linked above).