I have seen many biographical films about artists in the music biz, many of them were really good, while others were just ok. The only problem with these type of films, is that they are limited to 1-1/2 to 2 hours to tell the whole story. Often times that is not enough, so unless you know the backstory, you'll miss out on some of the nuances of the film.
Straight Outta Compton, which opened August 14, does not escape this pitfall, but it is an excellent film that stands on its own. This is the story of N.W.A., who rose to stardom by creating a unique sound, with in-yo-face lyrics that made people take notice.