Answer:
That depends on who you're asking. Most would say he was a madman, due to the Holocaust, but before that Hitler revived the broken German economy and returned the country to dignity after its embarrasment with the Treaty of Versailles.
Hitler's behavior was characteristic of a mental disorder. There is still much debate as to whether Hitler suffered from Huntington's Disease. Since he died prematurely if he in deed had Huntington's disease, then that would explain his irritability, burst of outrage, cruel methods, etc.
His behavior was definitely not sane. It is hard to diagnose someone who has already passed on.