I want to say one thing this occasion, though, because the implication in a lot of what I'm hearing seems to be that certain types of unsolicited reader feedback aren't appreciated and therefore, shouldn't be offered.
I have a hardline approach to feedback which is namely that if I didn't want unsolicited feedback of any kind, I wouldn't be posting what I wrote in a public forum--I would be getting feedback only from private circles from people I knew and trusted, either to flatter me or to give me the cold hard truth.
Odds are that if you're posting fanfic in a public forum of any kind, you are going to get unsolicited reader feedback. And, to me, complaining about it once you've gotten it makes you pretty ungrateful.
We all have to deal with the occasionally stupid, petty, condescending, or mean-spirited review. All of us. It doesn't matter if we're new or old or have a million fans or only one fan. Nobody's experience with feedback reception is perfect. But assuming that your opinion doesn't matter before you've given it is a total shame, because to me it negates the entire process of what the fanfic community is ultimately about.
I don't have time to review all the fics I read. I don't have time and I don't think that's a bad thing, because I generally won't take time to leave reviews for fics I didn't enjoy, whereas if I really liked your fic then I'll try and write something even though it's just a one-liner usually. I appreciate everything I read and every piece of feedback I receive. I don't reply to it all right away, but that's not just feedback, I have serious trouble replying to any kind of correspondence right away. I don't feel guilty about that--but I do wish there were a more standardized way to make everyone feel that their comments and their responses in any form are totally appreciated.
So I guess I just want to say to everybody, and make this clear, that if you've ever wanted to say something less-than-positive or leave a piece of constructive criticism for something I've written, I will welcome your opinion. I don't care who you are or if we've never met. I am a theatre reviewer, don't forget, and I always tell everybody before I beta for them that if I didn't like their writing so much I wouldn't be so hard on it. I can't personally understand why anyone would want to purposely be mean-spirited about a work of fiction simply because they can be--that, again, negates the whole point of community and shared enjoyment of fanfic--and I do agree with people who feel that purposely aggressive sorts of reviewing and critique seem to be going against the spirit of fanfic feedback. But if you have anything you want me to know about the way I write fiction that you've been holding back from for whatever reason, I just want you to know that there's no need. I will welcome it.
To me there isn't one single source of review that is preferable over others, because there isn't one single source of reviewer. We all have different tastes; I'm not going to expect a Snape fan to read my H/D fics the same way that an OTP H/D shipper would. That doesn't mean that when the Snape fan takes time to review my fics it means less to me. And the standard one-liner doesn't necessarily mean less to me than an all-out critical review, whatever the motives behind that review, or whatever the basis for the reasoning of the feedbacker. It means a lot to me that any of you would take the time to read the fic, let alone review it, regardless of what it is; and if you've taken the time to read with a critical eye and be honest about your reactions, I'm going to value that, even if I don't necessarily agree with it.
And, you know, every few months or so, reading all the discussion about literary critique v/s con-crit v/s one-liners v/s people who don't review at all always sort of makes my head hurt. I don't understand why people just can't be grateful--grateful that we have places to post our fics without getting arrested for copyright infringement; grateful that we have other people to read them and whose fics we get to read; grateful that sometimes people take time to share their reactions with us.
I don't honestly get the sheer amount of negativity that can result from the mere process of feedbacking fanfic. I probably never will. But anyway consider this a blank slate if you've ever been unsure about my reaction, and feel free to give me your honest opinions. I'll be grateful.