This drama is just awesome. There are so many great things about it:
-Many memorable scenes
-The retro feeling
-The 90s kpop
-The amazing cast
-Everyone had great chemistry with almost everyone.
-Amazing parents (this is a first for me after 30+ kdramas)
-Gay storyline in a kdrama that feels almost natural
-Good cinematography, especially outstanding for a slightly aged show
-Amazing ending

The biggest negatives for me were the mandatory love triangle and the older brother, despite the older brother's amazing flashback romance I just couldn't accept his predatory behavior as a teacher. Normally I don't care about age gaps at all, but this just irked me. Also they dragged on this semi dating bullshit for way too long.