Firstly, as opposed to some reviewer's notions, this movie has nothing to do with the GDR. Actually, it is about a group of teenagers from the Ruhr area, deep in the western part of former West Germany, (in)famous for its coal mining heritage, working class attitude and direct and loud, but hearty people. The story derives from short stories by Author Frank Goosen, who grew up in this part of Germany, and it actually connects them quite well in the first half of the movie. The second half is your classic teenage romance dilemma type of movie, as seen before in many tenn comedies. Story-wise, there is not much more to tell here, and if you are looking for complicated plots and fresh ideas, then you should indeed look elsewhere. But If you do, you will miss some good things.
This movie is, in my opinion, best watched as a piece of 80s Ruhr area nostalgia, and as such, it does a very, very good job. It is certainly not a history piece, as it takes a look at a very distinct region and time period through very rose-tinted glasses. But that is the beauty of it, really. Think of it as a cinematic equivalent of all the good memories one has when going through a stack of old postcards and family photo albums.
Another thing that makes this worth watching is the cast. Apart from a plethora of famous German actors in small parts or even cameos, it is the young actors in leading or supporting roles worth watching, often at the start of their careers, or at least not long into it. Especially Maximilian Mundt (How To Sell Drugs Online Fast) and Milena Tscharnke (Soko Hamburg, Ende Neu) are interesting to watch - and indeed to watch out for in their current and future careers.
The set designers and location scouts deserve to be honored, as well. They did a great job and certainly contributed a lot to making this work as a somewhat nostalgic, enjoyable pastiche of life in 1980s Ruhr area.
As a movie based on Frank Goosen short stories or books, this movie does a better job than others before it. Goosen seems to be somewhat hard to grasp for filmmakers. Much more seasoned and famous directors and screenwriters than Matthias Kutschmann did considerably worse trying to make good films out of Goosen's work and staying at least somewhat faithful to it. While this is certainly not perfect, it is, in my opinion, the most successful attempt at doing Goosen's stories justice.
In the end, this movie is not challenging or especially innovative, and it certainly has it's flaws plot-wise. But it is very good at evoking nostalgia, especially for those who actually lived through this time in this part of Germany. And for that, I think it is well worth watching for all of those with roots in the Ruhr area, and those who are curious about it.