tHe Reichenbach Fall is my favourite episode.

His Last Vow is ruining the characters personalities. It is stupid to defeat Magnussen by shooting him. Not using Sherlock's 'brilliance'. Like the way he did to Irene or Jim. Where's the mind game?

^Late answer, but this is exactly the point. Sherlock always mocked emotions and sentiment in order to avoid distraction from his mind game. In the third season and moreover the last episode he becomes the victim of everything he repressed all these years. His emotions finally grew enormous and so powerful that they broke all the walls he had been building all his life to protect himself. In the face of this big and destructive change, his brilliant mind is unable to react in the usual way.