I'll jump in.
Certainly, one of the most difficult things is getting this balance exactly right. As a former chief privacy officer, I can tell you that it's extremely frustrating. On the one hand, you'll have people saying that it's too short, that you didn't disclose this and that. On the other hand, if you put everything in your privacy policy, you get accused of having a document that's longer than the Declaration of Independence.
I think we're starting to move toward models, and the web itself provides a great model for this. We're seeing layered policies where all of it is there, but it's presented through a series of hyperlinks that allow users to get very quickly to the aspects that are of particular concern to them, and therefore they can inform themselves and make an educated choice about how they want to proceed.