I have to admit i like the game, it's really addicting. I'm Rank 21 now and have 4 Rare Idols (1 from the, 1 from a ticket, 1 bought with 5 love gems and 1 found with normal scouting). I have idolized all 27 normal idols and i'm working on maximizing the bonds with them all. And gathering 50 love gems to scout for 11 rare idols at once. Apparentely if there is a special event you are guaranteed to get an ultra or super rare idol if you do so. The problem is, the current event has the 2 idols i don't like (Nico and Hanayo).
About the music: I like the songs i have unlocked so far, they are all good. Unlike Idolm@ster there is no song i really dislike, stuff like Kiramekirari or Ai Like Hamburger. But there is also no song that blows me away, like eDEN, Yakusoku or relations. There isn't even a song i really like, akin to Alright*, Me ga au toki, Little Match Girl and many many other im@s songs. In other words: it feels like they all sound like the same, on a solid level.