Funny you should mention feedback - I haven't had a single bit since I came on this site, yet I've had a lot of hits there and people have been reading the stories. (I hope).
Strangely, mostly the only severe critisism I get is from Lynne, (ic50) who's got so far 'into' the stories, she's sorted out every little niggle that I've managed to get wrong. A few blundering errors I corrected before I re-posted here on GA. I managed to get two characters at two different places at the same time! Not good!
Apart from that I think I only ever had one really scathing email, so I took on board what he was saying, but din't take it to heart. That's a definite no-no. It can put a writer off for good. Not me, I must have a thick neck! I think as long as the critisism is justified, then fair enough, but people should never knock a fantasy story too much, because what's real to one person, may just not be for another.
Real stories are a different thing. If the reader doesn't want to believe you, tough. That's up to them.
I tend to write with a 'fly-on-the-wall' style mostly, but with the central character's thoughts written down as a plot to maintain continuity and develop the character.
Mostly it's me anyway - oh gloom what am I divulging here? - or written in the first person maybe.
So the crux of the matter is, be fair in your critisism, but don't batter the poor author under the table with a baseball bat. He/she is only trying their best to please the majority of readers. After all, most of us are only amateur writers. (I can think of a very few who ought to take it up professionally mind you). And did you have to pay to read it? No. So why moan so loudly?