I've been waiting for a Jieun comeback for a while now after we got a few from Titsung in the past couple of years.
Reviews for songs like this are the hardest. It's not good enough to write a decently-sized article explaining why I like the song so much and it's not bad to the point where I want to exaggerate how bad the song is.
The problem TS is having with Jieun is that they really don't know what to do with her. Honestly, my favorite Jieun solos have been her ballads, but they're trying to make her "compete" with Hyosung with these dance songs. "Bobby Doll" is alright, but it feels like Jieun is out of her element.