Well, despite all the "juvenile behavior", Anonymous is a force to be reckoned with. They mean it when they say "Expect us.".

I also think the fact that they don't care how you perceive them (by acting juvenile or otherwise immature) is one of their greatest strengths. Believe it or not, but it frees you from a lot of burdens if you don't have to be polite and politically correct, and makes it a whole lot easier to actually do something (whether or not that something is good and/or justified is certainly debatable).