The ratings are a big clunky. I've personalized my rating preferences as much as I can, and rated each game carefully and honestly, and still have games in my ratings list that I like more rated lower than games I like less. There are games I like that have bad art that are better than games I like that have great art, but because I am honest about the art, the entire rating suffers... even though I have the "art" importance slider as low as I can make it.
Mostly, the game ratings are just fun. Put time into writing a good written review, and everything will take care of itself.