As many have mentioned, the child actors were awesome.
Once again Park EunBin delivers an amazing performance. How can she be so good at singing, acting and everything! This drama finally made me her hardcore fan. The other cast were amazing too.

The love triangle was realistic, not annoying and healthy. It was one of the best handling I have seen in a any drama.

The songs and the performances are ont of the best parts of this one. So many moments gave me goosebumps!