I wonder how anyone manages to write music reviews. It seems so subjective to me, and music reviews I've seen seem to depend on you knowing as much about music as the reviewer, which is pretty useless to most of us. I guess if the reviewer says "This music is like A, B, C, and D" and you've only heard of C but you like them then that's useful. But it's hard to write a music review unless you do know that much. I can say that Pink Floyd moves me to the bottom of my soul, but that doesn't give you any idea of what it is that does that to me (I'm not really sure myself) or whether it would do the same to you.
Books and movies are easier; you can say whether you liked the characters, whether the plot made sense, etc. What can you say about music?