The Song Fight Bulletin Board

So I'm currently working on my music website and just for the fun of it I want to make it easy for people to review my songs. To that end, one part of the review things I want to include is a set of scales people can rate things on. Now I ask myself, what scales make sense?

For the last two rounds of reviews I used the Arbitrary Review System as invented by myself. It rates songs separately in five different aspects: composition, lyrics, feeling/vibe, performance, mix/engineering. Made sense to me when I thought it up, but can you think of a better or more interesting set of categories? Or anything else that might be interesting to see in reviews that people tend to forget to ask about?

The catagories themselves might depend on who your audience will be. Nearly everyone on SF is a recording musician, and so our reviews take mix & engineering as seriously as performance or songcraft.... but I might not expect the average listener to have the same appreciation for certain technical details that we involve ourselves with around here.

All categories would be completely optional, i.e. everyone would be encouraged to rate only those things they feel they have a valid opinion on.