Average.
Especially because of many historical inaccuracies and many of the actors having been really badly miscast (with the notable exceptions of Derek Jacobi as Adolf Hitler and John Gielgud as Speer Sr.)
Rutger Hauer on the other hand, is so unbelievable as Albert Speer that it almost hurts...
Other miscasts include Dr. Goebbels, Magda Goebbels, Herman Goering, etc., just to name a few.
Also, the portrayal of some characters is historically completely wrong. The Best example is Magda Goebbels, who is portrayed almost as a regular, 'normal' person, even with moral doubts regarding the situation. In reality, she was a bigger Nazi than even her husband (if that is at all possible), who killed her own children single-handedly so that they will not survive the demise of the Third Reich.
If you want to watch a better version of the same story, I suggest the German version 'Speer und er', which was much better.
All in all, watchable, but nothing to write home about.
Review of Inside the Third Reich
