it's been a while, so I'm ready to review fully 
First of all I'm so glad one of the Twice member went solo, it's such a good opportunity, I hope my girl Jihyo is next
So POP is such a bright song and so is the MV. On first listen I couldn't tell which was chorus but then understood. I like it now more than when I first listened to it, tho I think there are some songs on the album which are better, but this is more what public listen to material so I understand why they went with it. My favorite part is the last verse, it's very catchy and addictive. after chorus pop sounds are also good and very memorable. I don't know if I am going to listen to it very often in a long run, but right now I'm enjoying it. This is that bubble-gum twice sound that public missed, I hope she gets her hit, she is doing well. overall I think it was a good debut, suited her and her image. Her outfits are absolutely gorgeous too 
