He’d be surprised that some of his ideas were fully realized. Current Germany is really an evolution of Nazi Germany - mind that Nazi Germany was a national socialism, a system that takes care of their own Aryans. Now it’s just extended to take care of German citizens, including those of non-German origin.
He’d be surprised that all of the companies that used Jewish and Slavic slave labor in de*th camps are still here! (Volkswagen, Bayer, Siemens).
He’d be surprised that country that lost war is actually a long term winner, being biggest economy on the continent.
He’d be surprised that most of his followers quickly forgot about him and started calling themselves “victims”, victims of infatuation with Hitler’s charisma. A lot of his associates lead very cozy life in South America afterwards. And a lot of war criminals held notable positions in post-war Germany as city mayors and officials.
It might interest him that his ideology is still alive among some Germans.
It might disappoint him, that Berlin, from a militaristic capital, converted to ethnically diverse city.