Let's take a look at the positive. This is or could be perceived as a master class in acting. The movie itself seems to be free of restrictions (and clothes for that matter) and you should be aware of the nudity. There is no visible penetration by the way, but you do have male self pleasuring (explicit and vivid).
Having stated that (in Germany the movie still got the 16+ rating), that should not play a role for or against the movie. The characters have issues which become even more apparent during a visit from the "outside". Their circle is clear and somewhat stagnant, this outside influence kind of gives the movie a bit of a new edge, but nothing that is sustained. We get back to the old "craziness". Which may be the point of the movie, but does not make it more attractive or viewers more excited to watch it (if you'll excuse the pun)
Having stated that (in Germany the movie still got the 16+ rating), that should not play a role for or against the movie. The characters have issues which become even more apparent during a visit from the "outside". Their circle is clear and somewhat stagnant, this outside influence kind of gives the movie a bit of a new edge, but nothing that is sustained. We get back to the old "craziness". Which may be the point of the movie, but does not make it more attractive or viewers more excited to watch it (if you'll excuse the pun)