Well this is my favorite kind of story; going back in time or going into the future!  Love them!
This series is probably my favorite I ever watched, or right in the top 5.
I liked all the actors, but Ryeoun was definitely my favorite, just something about him and how he played the part, he was fabulous I thought!
The only thing (which I agree with others) is the last 2 episodes were rushed, I would have loved more on what happened in the future, just wasn't enough of it. But still loved loved loved the series!
I thought it was very emotional at times and so so so darn sweet and touching. I simply loved it.
Also Ryeoun, I think I found a new favorite actor (or one of them).... :)
Worth the watch for sure!!!!