Matthew Yglesias argues that their lack of specific demands limits their effectiveness:
I’ll cheer. If we do one down by the Eccles Building, I’ll show up. But when the lodestar of your movement is to say, “The one thing we all have in common is that We Are The 99% that will no longer tolerate the greed and corruption of the 1%,” it’s difficult for me to get excited. You have to have a dream scenario in mind. What if the protests are super-popular, the crowds are enormous, and the inconvenience to the high and mighty becomes intolerable? What if the bad guys decide it’s time to consider a surrender? You want them to come out, address the crowd, and do what?Image: "Participants in a march organized by Occupy Wall Street walked through the Financial District Saturday." (Associated Press, via the Wall Street Journal)
That’s not to say that slogans need to be wonky and boring. “Jobs with justice” is a slogan, not a specific proposal. But (when it works) it’s a slogan that does have some concrete ideas behind it about whose jobs would be impacted and what changes would constitute justice.