Right now I think Act-Age is in a good spot, but it needs to flesh out some of its characters soon if it wants to grab hold of a wider audience. As others have said, Yonagi is a cute dork, but the rest of the cast (save for maybe Chiyoko) don't have much character to their name. Akane (the other girl in the main group) has so far been the only non-main character to have some sort of development, but that seems to be already finished since her conflict with Yonagi has already been resolved. I want to learn more about the other characters in the main group as well as the actors from STARS.
In regards to Chiyoko, right now I honestly don't like her character. I don't think she's a bad character per say, she's just an unlikable character in my eyes. However, I think she can be a great "boss turned rival" character that the current arc seems to be building up to. If she grows and changes as a character, I think she can grow to be more likable.
Since we're not even 30 chapters in, I can understand the current state of the characters, but I hope the important ones grow beyond just the initial character they're introduced as.