I'm concerned that all reactions might be treated as good reactions. That is, that there is no way to politely disapprove. Does anyone have any more details on this?

I suspect facebook and company will come up with a solution to the problem of how do you indicate that you saw something without commenting when it's not socially acceptable to 'like' it. For example a funeral announcement, you don't want to 'like' it but you want to say 'thank you' or something yet you might not want to comment.

A real dislike or hate button would simply result in a lower signal/noise ratio. Maybe new types of bullying where lot's of people 'hate' on somebody.