A writer-friend thrusts a sheaf of papers at you and says gruffly, "I wrote this. What do you think?"
Helpful feedback is less about what you, the reader, like or dislike than it is about helping the writer determine what works or doesn't work. There are nearly 7 billion or so people on this planet, each with his own likes and dislikes, and the fact that you don't care for a piece of fiction is not a good indicator that it's crap. That's just your personal taste.
What is more helpful is providing feedback on:
1) Characters: believable? interesting? consistent? Does it feel like the author likes them (even the mean ones)?
2) Dialogue: realistic? Does each character have his own voice, so you can tell who's talking, even without dialogue tags?
3) Structure: is the plot believable? does it hinge on the actions of the characters, or the whims of fate (aka deus ex machina -- which was perfectly acceptable in the days of Greek tragedy, but today is considered to be really cheeseball)
4) Voice: Does it match the piece? (You don't tell the story of starving sharecroppers in Alabama with the voice of an English butler (generally). Is the voice consistent, or does it slide in and out of other voices? Is it too intrusive?
5) Language: how well do the metaphors work? Do they fit seamlessly into the narrative, or feel like they were shoe-horned in because the author thought they were cool?
6) Narrative, action and dialogue: are they balanced, or does the work lean too heavily on one or another?
Last Week's (Month's) Winners:
Steven G (who has no blog, despite recurring requests) and Berowne at Savage Reflections
This Week's Prompt:
Actually, what I'd really like is some guidelines, similar to those listed above, for poetry. When someone asks you to provide feedback on their poetry, what do you look for?