Major Studio | INTERFACE : Final Project, Online Rating Systems

Below is a short analysis of 4 sites online who are known for their rating and review systems. I guess I had never realized how each of them differ, but they certainly do. Each choose a familiar symbol, number, method which could be why they all feel very much the same when used. The rating system I intend to employ in JustANote.net would be larger than this going from -10 to 10. Mine would differ from these 4 in its use of negative numbers, however this addition makes sense in purpose of rating the content (reflecting negativity or positivity).
Another note to make would be the connection of the reviews and comments with the rating. Should my users have an opportunity to comment about their rating as well as simply vote?