Time Travel is one of the best topic for a drama, but it is also a very difficult topic: if the script is bad, no matter how beautiful the storyline is, it will be a flop. This drama has everything a time travel drama should have: good plot, good script, good casting and good meanings. The plot is full of twist, emotions, changes and it takes you to another world, the world the main character is experiencing. Because it is a drama that rounds around the main character: even if the others are important, the feeling you have is that Sun Woo is fighting alone with his own story, because he wants to change something he cannot change anymore. I found this drama awesome because he makes you think about life. "Changing something bad in the past maybe cannot bring you happyness." If something bad happens you have to work alone on your own happyness, not trying to change your past or your fate. This is the meaning of this drama in my opinion, and it is a good meaning. I think this drama is amazing. Even if it doesn't allow you to understand everything (but this is part of the script), it makes you think of everyday life while the plot is a time travel so a 'fantastic' one. I absolutely loved this drama and I am planning to rewatch it. I reccomend this.