Yes, Its just not your average fantasy drama. I've seen many of them and by far this is one of the best.

I love how the story being put together. It may seem a bit slow but for me it was just nice.
The first 2 episodes got me hooked real bad that I began following it every week. I watched it with the expectation of a sad ending. But the writer decide otherwise. This drama gave a very subtle ending. Its kinda rare for Kdrama-land to give a satisfying ending to most of the important characters (usually only the main ones).
I think the message from this drama is.. whats meant to be will happen regardless and those fated together will always end up together.

Here in the drama there's two main couples (sort of). Where each of their lives intertwined each other and eventually became sort of family.

The actors:
The chemistry between Seo In Guk (SIG) and Park Bo Young (PBY) were super amazing. You can see this on their behind-the-scene clips in youtube.
SIG portrayed his character well, being "Doom" (the destroyer) he had to have cold eyes and expression and he nailed it. SIG acting skills never disappoint and this drama just another prove of how amazing he is.
PBY is cute, bubbly and super friendly. I liked her character here as Tak Dong Kyung a lot. A selfless, patient and caring person that she is always putting everybody else above her. Thats why Myeol Mang always said that he existed for her, as if the Deity's is rewarding her for her good deeds in life.

Lee So Hyuk (LSH), Shin Do Hyun (SDH) and Kang Tae Oh (KTO) chemistry are also another reason to watch this drama. Each of them portrayed their character well.
LSH often play very cold characters in dramas/movie. So this time he has a cold look but soft heart character which kinda suit him pretty well. And finally.. He got the girl in drama-land. The way he look at SDH character (Na Ji Na) is so sweet. His eyes seems like shooting hearts at her and he speak softly only at her. Whilst he is being all prickly with other people.
SDH is very good at portraying her character. A quirky yet kind-hearted towards her percious Tak Dong Kyung. She is like the older sister who protects her siblings. I also love how she is very endearing towards Sun Kyung although he is not her real siblings.
KTO well he is just super cute and handsome especially when he smiles. His acting in "Run On"was my favourite but lets add this one as well. He portrayed it really well. Although in this drama he came out a little bit spoilt but he managed to grew up in the end and be a responsible adult.

Lastly not forgetting Dawon (SF9) as Sun Kyung, the annoying yet caring little brother. I love how he grow close pretty quickly to SIG and LSH taking them both as his brother in law. He is super protective of his sisters (yes he take Ji Na as his real sister) although he can be annoying and joker some times.

Overall.. all actors portrayed their characters very well.
I've read a lot of negative review on this drama. But have a look yourself just the first 2 eps.. see if you like it. For me the story is just as warming and nice as it is. Again its not your average kdrama.
Not all fantasy dramas are good but this is one to look out for because it gives you warmth and smiles as you watch it.
Oh and the OST are super good. SIG sings one of it and I read somewhere that he wrote the lyrics himself. The song is very touching and has nice tunes to it. Have a listen to it. (Title: Distant Fate by Seo In Guk).

Hope you will enjoy this drama as much as I did. Thank you for reading ^^