Grades make the most sense for game reviews for me, or, put another way, converting a star system to grades is the best way to think of it. 0-star = 0-59%, 1 star = 60-69%, 2 star = 70-79%, 3 star = 80-89%, 4 star= 90-100%
I find it very important to think of games this way because technical incompetence (much like failing comprehension or ability with grades) is such a large part of gaming. There needs to be that large bottom half of the scale to allow for certain technical failures, which render the game "broken". A game that doesn't work for several reasons, no matter how great the story or graphics, gets a failing grade due to it being broken. It might get a High F for effort, but it still fails the fundementals. This is different from Filmmaking or movies, where no matter how technically competent the images you put on the screen, the movie will play and you'll see the movie. You (the filmmaker) cannot fail to show what you meant to show. Games, OTOH, can have technical issues that prevent you from seeing the game. This also makes meta-reviews less meaningful, because technical issues for one person might not appear for another, drastically increasing the stddev for reviews.