While it comes up again throughout the series, skip the pilot episode. It'll kill your interest immediately with its terrible character introduction and plot set ups. It's honestly absurd how awful it is. The rest of drama was quite entertaining and had some fascinating plots and ideas involving jealous, dealing with regret and pain. It's not perfect at all. For example, the scenes where they go to England are very, very, very clearly not in England but Australia. The trees gave that away instantly, let alone when the people spoke. As a Brit, I was insulted that they thought they could get away with that. Many people found Han Da Jin to be annoying (same with most of Gu Hye Seon’s characters, so perhaps it's just her) but I thought she was a good solid character to get behind. Her actions are just, although fueled by a hot temper which makes sense as she is still in training. And gave a nice contrast to the prickly, perfectionist Kim Yoon Sung. The characters were solid, although the villains arc are completed way too quickly.