I've watched this multiple times, and I've enjoyed it. Every. Single. Time.

The falling in love part of the overall storyline is so soft and beautifully executed. It's not a slow build-up, but it also makes sense that "yeah, these two are obviously in love." There's no questioning it.

The last time I watched it, I actually watched it twice; from start to finish.

The ending is gut-wrenching and impossibly sad, and you wish that Ji Hoon could have been a little bit more selfish; but his actions are totally logical because he dies to protect the child version of the man he is love with.

The ending is absolutely gut-wrenching and impossibly sad.

There IS a glimmer of hope to be had in the ending, though, because of the time-loop aspect.