The movie is about a program in a prison that has convicts performing Shakespeare plays. There are two aspects about it that are really amazing: one, the convicts themselves, and two, the Shakespeare aspect.
First, the convicts. I don't know much about convicts and what it's like to be one. I have strong views about the prison system and how messed up it is, etc, and a strong belief that society presents prisoners as thoroughly evil people, and denies them a real chance at rehabilitation (an amazing film that deals with this, by the way, is The Woodsman), but it's pretty powerful to actually hear the prisoners themselves talk about their lives. One very clever aspect of the film is that it doesn't tell you about the crimes people have committed right off the bat. As the film progresses, it gradually introduces clips of the men themselves revealing their crimes. These are often absolutely devastating moments. And their accounts, and how they make sense of their lives, is really fascinating. It kind of makes you think about how people make sense of evil, to put it in rather extreme terms. One guy, for instance, describes the multiple crimes he committed, and how he tried to become "good". But he always seeks an external cause for his actions - it was the people he was with, the place he lived, etc. Another guy describes his crime and then talks about wanting to achieve some kind of redemption, and contemplates how he could do that. It's intense stuff, and all the more so because it's interspersed in these moments where they're just going about their everyday lives in prison, and really seem for all the world like "normal" guys. Although the film doesn't really push the point, the movie does also illustrate how messed up the prison system is - indeed, I suppose it would be difficult NOT to.
The second aspect is that it makes you realize just how brilliant Shakespeare really is. I mean, the way these guys relate to these plays and the various themes in them, and how one can use the plays to consider what it means to be human, and the nature of good and evil, is just amazing. The friend who recommended the movie to me was saying how it made her want to go out in the world and teach Shakespeare, because it made her see how doing so could make the world a better place. Watching the movie - I completely understand why she felt that way, and I absolutely shared the sentiment. It's a really powerful example of how literature can inspire philosophical and ethical reflection in these really amazing ways.
Like I said though, the movie somehow doesn't quite achieve the greatness that its material deserves, and it's sort of hard to explain why. Nonetheless, I think it's absolutely worth watching - I just wish it were better.