"Weird" Al Yankovic has not been nicknamed Weird for nothing. And the semi-autobiographical, semi-schizophrenic movie-stub clearly confirms this. Moreover, I do not remember any autobiographical film, where the hero of autobiography would play a minor role while also a real person.
There is no point in writing about the plot - the title of the film describes what is happening on the screen.
But it makes sense to write about Radcliffe, who has once again demonstrated that he is an excellent actor with potential and that he is ready to star in a variety of films. Certainly, seeing Radcliffe/Jankowicz in the same shot, you begin to understand that the curly hair, mustache and glasses are just a convention, and the main thing is how to perceive the world and how the world perceives you: only as a Harry Potter/musician-parodist or as a high-class actor/writer of original songs. The choice of Radcliffe for the lead role (and even more so the coordination of him in that role with "Weird" Al himself) is by no means accidental.
Actually, the film can be divided into 2 parts: Al's relationship with his parents from childhood to adulthood and Al and the pop industry. That said, if at the beginning of the film (childhood) you watch and still naively believe that it was like that (the dialogue with his father about the factory and what it does is great), then after the transition to the second part you realize that the viewer is being unkindly mocked. So it gets harder to take in the "autobiography" until you realize that the entire movie (including Radcliffe in the title role) is itself a parody of the autobiography.