It is my sincere opinion that despite all the love/hate floating around about the drama, it really had only one true problem - this was a 20-24 episode drama shoved into a 16 episode one.
Think about it - the most consistent criticism? The logic leaps, lack of explanations and editing. Well, to me, that is not having enough time to explain what's going on adequately. We had to guess.
I think given this, the writers did leave enough clues TO figure it out, despite the rushed feeling.
I enjoyed this drama - the production values, cinematography, acting and OST were excellent, and the story very interesting. Again, biggest problem I had with it was that sense of being rushed, of things left out or not fully explained.
Still, the ending did indeed wrap up EVERYTHING I wanted it too - which thrilled me :D
BTW, I thought the two leads had excellent chemistry :D