It very much borrows from 'To be or not to be', the 1942 movie of a theatre troupe playing a piece on Hitler, when at some moment in time the actor is needed to step in for the real Hitler. Great fun.
And here almost everything is in parallel, except that the actor has to play Erich Honnecker, the former strongman of the former GDR.
The whole lot comes across totally hilarious, though probably only to native Germans old enough to have had sufficient contacts and knowledge of the former GDR. The typical East-German dialect and the typical mumbling of Erich Honnecker, the typical Berlin dialect of the daughter, and the actual occurrences in the autumn of 1989 are almost a prerequisite for a full enjoyment of this movie.
Original clips like the expatriation of Wolf Biermann are used to drive the plot. (I guess the majority of Germans wouldn't know of those things that happened in 1977.)
One can but laud the ability of this movie to being hilarious by just scratching along a very specific reality. And one could at the same time question the undertaking to do that 28 years later, and based on plots and scenes and a personage and language dialects taken from a very specific reality and most probably only working in exactly that reality.
The current rating of 5.5 is not realistic. Those unacquainted with the background will surely find this movie very artificial if not boring. I'd feel likewise, had I not acquired this background knowledge through some decades of exposure to this system. From this angle I might as well have given a 10.