It is still cute and fun school drama. If you like Lee Won Jung in Hierarchy and want to see more then it is perfect - I think that you can even watch without first season.
So as I already mentioned first season - in my opinion it was so much better than second season. My biggest problem was cast change. As far as adding Ji Han was not a big problem or change, then changing main character to Yena......I am so sorry to her fans but her acting is not for me and I know it was her debut, but many idols debuting as actors did better. I loved this character in first season, in second I just could not watch it and there is no way to treat this character the same. It was better to just add new character.