After reading several book reviews on Amazon, I was surprised by how many reviewers judged books by their covers . . . by their titles even! Some critiques were the written equivalent of walking out of a theater and proclaiming: Wow! That movie really sucked. What surprised me even more was how many of these reviews were written by writers . . .
When evaluating any kind of art, it's essential to look past yourself--your tastes and experiences--in order to evaluate the work in front of you fairly and not personally. When reviewing fiction, for example, the question is not whether you 'liked' the story, but whether the story was good. Not the same thing at all.
Though not specifically prose, let's use the band Journey. I'm not a fan of this type of arena rock. Not a fan of much of the popular Journey catalog. But I'd give the group several stars if I were reviewing them critically. Why? Because their goal--to write and produce memorable pop/rock songs--has been met. Under the banner of arena rock, they are exactly what they're supposed to be with a few extras--Steve Perry's voice and a good guitar player.
Reviewing a novel or short story requires more than the ability to read critically. There must be some attention paid to author intent. In other words, the author wrote a horror novel. Is the novel scary? The author has written a coming-of-age tale set in revolutionary-era Cuba. Do the characters come of age in this Cuba of yesteryear?
When everything is lined up--great prose, believable characters and consistant conventions throughout--the criteria for writing a positive review have been met. And unless you're God or everyman, you have no choice but to give the writer a big gold star even if you didn't like his story.
The land of literary is far more subjective than it needs to be.