I just finished this after 16 hours straight and the only thing I can say is: masterpiece. From the silly moments at beginning, the "confusing" time-travel theme throught the middle - till the last scene, I loved every part of it. The writers did a really good job writing such complex theme like is time travel. There's no holes or things that u can't understand or think it's missing like others time travel dramas or movies I ever watched.
The cast acting was really good as well, specially from Alice Ke. The music is another important thing about this drama, u can notice that they're extremely connected to the history and do not serve as just background sound. Simple amazing.
I don't think I can get over this anytime soon. I just wish I could forget all I watched just to watch it again. But anyways, even not forgetting at all I'm gonna watch again, and again.