I've been wanting to do a rewatch for a couple of yrs now, but haven't got the chance.
I will not compare this remake to the original Japanese one.

Seo In Guk has been one of my favourite Korean actors since the beginning of his career, and I think he showed many different characters in his show.
In this one, he seems even younger than he was at the time (his undereye mole always get me) and in some scenes he seemed also vulnerable, if possible, nonetheless he managed to scare me and gave me chills from the very first episode.

I didn't like the female protagonist at first, but then I fell in love with the chemistry between her (Jin Kang) and Moo Young.

I clearly remember Yellow from Coldplay being in one of the episodes, and this already gave the OST a good vote from me :)

The story was not as linear (especially if I think about Jin Gook's choices and the police actions), but it was a good one.
I especially enjoyed the mistery around the main couple and the sad truth(s) revealed during the series.

Regarding the ending, I loved how the production decided to dress Jin Kang in white, pure from the beginning to the end, and Moo Young in black, almost indicating their "side" but also their bond, like the Yin & Yang.
Also, when Jin Kang comforts Moo Young at the end, it seems like she's giving him forgiveness and peace.

Highly recommend, I hope I can do a rewatch soon!