The acting by Klaus Maria Brandauer as Hanussen is top notch. He carries this movie. And all in all I really enjoyed it.
Only the title is a little misleading. Because I never got the feeling it portrays the historic Hanussen. But then again movies seldom stay true to history. But at least they got all the major events right and even Hanussen's stage performance and probably his charisma...
But his character... well, I just feel that he wasn't the kind of person that is being portrayed in this movie - AT ALL! This movie portrays him as an opponent of the Nazis, when in reality he was more of a supporter who fell out of favor due to factional infighting and some miscalculated movies on Hanussen's part.
A lot of people have noticed this and many have asked why he is being portrayed in a purely positive light and as an opponent of the Nazis when in reality he was more like one of Hitler's most important supporters at the time. Personally I think they intentionally altered this aspect. Consider it German censorship. As you can clearly see by watching this movie, German censorship works very different than U.S. censorship. Germans have no problems with displaying tons of unnecessary nudity, sex, alcohol, drug use and swearing - sometimes even in children's movies. But having the protagonist of a movie be a leading Nazi? And on top of that a Jewish Nazi? No way! People in Germany of 1988 weren't ready for that kinda stuff.
In 2007 the Germans made a movie called "My Führer" which also seems to be VERY loosely based on Hanussen. Only this time they finally included scenes of him actually teaching Hitler - something they obviously weren't yet ready for in 1988.
So I actually kinda liked Klaus Maria Brandauer's "fictional" Hanussen more than the historic one - he is definitely more sympathetic. So as long as you separate the Hanussen portrayed in "Hanussen" from the historic Hanussen, then it is a very enjoyable and touching story.
Oh and I feel I have to note that the English subtitles I had aren't exactly the most accurate. A lot of times the subtitles seem to say something completely different than what is being said in German. And while the acting of Klaus Maria Brandauer is awesome, the acting of some of the supporting characters is awful. Now this sounds like a lot of criticism, but actually the movie is still pretty awesome and truly deserves 9 out of 10. If you liked movies like "The Prestige" or "The Illusionist" then this is a must watch!