The plot is crazy
The characters are not realistic
The music is so so so horrid *alllmoossttt pppaaaaarrraaadiiissseeee
This drama is so bad, it is addictive.

BOF throws away SO MANY insanely illogical plot devices week after week yet there i was, faithfully waiting for every new eps to watch it UNSUB first then SUBBED.
This is a testament to the great acting and chemistry of all the actors doing their utmost best with what little writing they have.
I believe this show was carried on LMH and KHS having surprisingly great chemistry.
Seeing KJH is bonus and KB is whipped cream with cherry on top.

I have seen the TW version, Japanese version and this K version.
I have to say the Japanese did it best, may be due to the fact that the original material is Japanese hence it converted seamlessly into dorama.
The TW version was also good - F4 were the original oppas before there were kdrama oppas.
This K version was crazy bad - you become used to the badness of it all and just enjoyed all the empty calories.