The problem with Battle Royale is that, even though the story does contain some good commentary on tyrannical governments and control via the media, and does a great job of presenting every significant type of protagonist within its cast, it also has a story. And that story relies on lots of teenagers experiencing bloody unclothed deaths to be entertaining. And balancing out these different things is quite difficult.
The story ends up being good as a character study, a slasher, and political commentary, which is a lot more than most stories can say, but it still doesn't change that it could have been _great_ in any two of those things if it had let the third slip.
Like the political commentary, for instance. Who cares about political commentary? Oh, that's right: book critics. Well fuck them. We already know the nazis are evil, and while Big Brother does get a few write-in votes in every election, those are jokes. Drop the political commentary except as it helps with the setting, and focus on developing awesome characters and bloody unclothed death.