The only think I can think of, after completing this series is: Why?! Why waste a good line up of actors (and crew, I assume) to mess it all up with an inconsistent and perverse storyline.

Spoiler alerts now, do not read any further if you don't want to:

How can a brother talk about the love for his sister, when he does anything to keep her away from the man she loves, including stabbing him? The only reason I have come to conclude is that he purely out of selfish reasons didn't want the truth to be found out by the boy and the role he played in his miserable life. All in the end we find out he knew all along that he was the 'lost boy' and that his sister and that boy were very close friends before. As someone who has lived with guilt all his life he should have been extremely happy to have finally found that boy and see him reunited with his sister. Can't get around the twisted minds of those plot writers and actually feel cheated by them. What a waste of a basically interesting story 'bad boy can become good if he's given the chance'.
Still, the actors tried their best and drew you into their drama. It's only a pity that there were so many inconsistencies and unexplainable behaviour (sister is all la-di-da with her brother after hearing he stabbed her boyfriend!?).
So, all in all, a lot of missed opportunities to create a strong dramatic love story.