Good start, but then it gets ruined

A lot of perfectly good film show their cards early, establish a unique premise and let the audience explore a topic at a leisurely pace, without much in terms of surprise. this film is not one of those films.

There's a more than satisfactory amount of boom-boom in the movie's trim running time.

This is a coming of age storyline that you've seen in one form or another for decades. It takes a truly unique voice to make yet another one worth watching.