Currently on Netflix (2016) this series is known as "Playful Kiss" for US viewers. I've seen the story before titled "Mischievous Kiss: Season 1 and Season 2," done by the Japanese. That series was undoubtedly influenced by this South Korean version, which was done first.
At any rate, I really enjoyed both versions. There are very slight differences but the core story remains the same: girl likes boy who could not care less about her... until events unfold that give her small bits of hope, like crumbs left on the ground to follow a path. It's how the story unfolds that draws us in. Many times I laughed out loud. Often I had a silly grin on my face. There were times I couldn't stop the watery eyes. I was rooting for Oh Ha Ni all the way - her character was just so adorable and spirited, and good. Oh, and she daydreams!
Anyone who enjoys love stories, no matter the culture, should enjoy this. I'm English-Irish American and I did! And I plan to watch it again. I could give spoilers, but why do that when one can just watch it to see if they like it? Don't look for perfection - look for the story, the intent - that's were the beauty is in "Mischievous Kiss" (2010).