***SPOILERS AHEAD***
The show is AMAZING is well written, funny, dramatic and romantic. It engages the viewer from the first shot until probably the last 2 episodes (Episode 19 and 20).
The whole series they keep telling you Samjang is destined to die to safe the world and sacrifice herself. However, a couple of episodes before the finale they reveal that she has to die at the hand of "her protector" aka Son-Ogong (which would have also sucked). Her fate is to die and she accepts it? Why? Not only that but she was supposed to die in a more heroic way which would have made me less upset with the ending but she is sacrificed for nothing only so that Ogong can have his glorious moment (which was not even well developed). The CGI dragon was a bit of a dissapointment but more than that the whole battle is in a single spot, with two swings of a sword the greatest evil the world has ever seen (for which they killed Jin) was gone, POOF, just like that.
Also, the last episode goes by with just memories from the series, not only I was pretty upset that they killed off (and yes I know this is a written book) BUT they should have honestly given them the chance to be together. The Spiritual Realm made them suffer enough truly defying her "fate" would have been not to die and to find a way, maybe use her new powers for instance? Samjang started developing stronger powers for the last 4 episodes could she not have fought Dae-sung? Really?
Then they give us the hope that Ogong was going to look for her in the Underworld but the show was not renewed so you will have to use your imagination on that one.
The viewers will always have a hard time letting go of their beloved characters but making it such a useless and worthless death is what really throws you off the cliff with this show.