I really enjoyed this little series.

The characters where natural, well written and well acted.
The production was pleasent and over all I really didn't think of production, cinematography, costumes, ect. Which is always a good sign, as it means I was sucked into the story.

Spoilers:
Ok, so with the time travel you have to go with the flow. Because it was not explaned, but I can get on board with that.

What I didn't get in the plot was, why Kang Ji Hoon had to go to the 'crime scene' alone and without anything to protect himself. He could have called the police or in the very least taken a bat or a knife along... I mean when you know what is gonna happen, you can change something.

If the writing team wanted to have him not change anything, so that everything happens the same way... ok. But you could have explained the reasoning.
I was intrigued by the different clothes that Shin Jae Woo wore in the last scene. It means something changes every time.

Spoilers End.

Apart from this I really enjoyed this series and will rewatch it. It's so nice to see characters that act so natural around each other and that accept themselfs without drama. Loved it!