Nietzsche was a brilliant writer indeed. Unfortunately, he was not nearly so brilliant a philosopher. His ideas are mostly inconsistent with one another once you get past the masterful command of the word. When it comes to expressing his insights, he can do so powerfully. When it comes to describing what should be done, however, one will often find that the idea underlying the eloquent words of chapter 1 is completely incompatible with the idea under the the words of chapter 2. As a general rule about most things, he wants black to be white and yet still have it be black.
As for his insanity towards the end of his life, it might also be that he actually tried to live and believe everything in his philosophy rather than any medical problem. No, seriously. To fully live and believe according to what Nietzsche taught would leave one virtually indistinguishable from a madman in the eyes of the rest of the world, since one would no longer be able to relate to the world as it now is.
