My basic impression of Monster's Ball is that it had a great deal of unfortunately wasted potential. The film itself was decent, and had a couple of major points going for it. For one, the acting was excellent all around. I was especially impressed by Heath Ledger, and even Sean "Puff Daddy" Combs turned in a solid performance. Oddly enough, I felt that the two main characters were the least interesting, but Halle Berry and Billy Bob Thornton help make them both more believeable and less dull.
Secondly, while I had some problems with the technical aspects of the film, it also had some extremely memorable shots. I found the cutting to be far too quick at times, but Marc Forster put together some amazing images through the use of mirrors. The scene in which Combs' character is executed is especially powerful, and I would not hesitate to say that the shot in which the curtain raises, revealing the audience and Combs' seated reflection seemingly sitting among them, distorted slightly by the glass, is one of the best I have ever seen and certainly the best in recent memory.
That being said, Monster's Ball has a ton of problems. First and foremost, I think its plot is fundamentally flawed. The film spends most of its time slowly getting rid of all of the secondary characters. This is a shame, because the film does little to attend to their departure, choosing rather to throw them away without sufficient depth of examination. In the end, I was left feeling that there was a tremendous amount of potential in the stories of these characters and a lot of potential depth to be sifted through, but that the film chose to sacrifice this opportunity to emphasize two other characters that are slightly more multidimensional but far less compelling and interesting. The movie doesn't really *go* anywhere, and it doesn't seem to have a whole lot to say other than "hey, wow, people can change. Surprise." Thus it lives and dies on the strength of its characters, which it unfortunately mismanages. Luckily, the acting peformances help mitigate this factor.
If you want a brutal, depressing-but-somewhat-uplifting movie, you could do a lot worse than Monster's Ball. Of course, you could also do a lot better.