I truly liked this drama. It was extremely addicting! The acting, by everyone, was simply brilliant and supurb. However, it did have flaws, which is why I couldn't, in all honesty, rate it above an 8.5.

Flaw #1.- There were times I thought the characters' thought process did not make sense.
Flaw #2- I was able to guess what was going to happen very early on. However, it was probably because I have seen so many dramas, but the plot seeemed to really mimic Gap Dong at times, which is what I kept thinking.
Flaw #3- There was one inconsistency that really bothered me, though I can see how it would be missed by some, especially if they watched it while it was airing. In the very first episode, a certain object is shone in one location. However, later on, it is changed to be in a completely different location, which changes the story.
Flaw #4- The ending does not really explain itself. You are left wondering what happened for it to end that particular way. It could have been on purpose, but I think that the writers could have done a better job at explaining.

Besides those flaws mentioned above, it was a really good watch. I would still highly recommend it to fellow drama watchers.