From the perspective of my own stuff?
I really appreciate negative feedback when it's constructive. It can be a bitter pill, but it helps me improve, helps me grow more confident in that field in the future (though there have been times where it did the opposite), and I tend to put more stock in the positive things people say when I know that person will also tell me when and what they think I did wrong. Furthermore, well-written criticism is great because you can actually follow the other person's thought process. It's not just 'I don't like this' - you can decide whether or not the criticism is relevant to what you're doing, because sometimes it really is a matter of opinion. And it's always helpful to get a gauge on how other people are reacting to your material. Meanwhile, people who enthusiastically agree with everything you do are encouraging, but if you have doubts, they're not going to help you with them.
I loathe getting negative feedback from people who won't put the same... intellectual effort? into something that I will, though. I get mad pretty easily when people scream at me for being the worst person ever for something that is opinion and they just can't recognize that, when they're the one that's wrong about the subject, or when they're trying to bring some third-party offense in that has nothing to do with the work. Look, I don't want to be an elitist about... anything, really. But we all know those people. The internet is full of them, and they're really not afraid to give you a piece of their mind as rudely as possible. It's really two coin flips on whether I ignore them, try to talk them down, or rip into them as passive-aggressively as possible.
I'll get pissed off if I see this kind of behavior towards other works I don't feel deserve this, though I'll refrain from getting involved unless it's an open forum. That said, I take sadistic glee in reading negative feedback (constructive or just 'you're terrible and you should feel terrible') to things I think are egregiously stupid. That said, the line between 'genuinely tried but is just really bad at what they're doing' and 'is not even trying' can be hard to spot, and you always want to play softball with the former. Err on the side of caution. The latter... it's a bit cruel, but if somebody is going to continually spam zero-effort crap around a forum, chatroom, or other discussion space, bitingly negative feedback can be useful in incentivizing them to stop doing that and either find a new hobby or actually put some effort into this one.
Oh - when giving constructive criticism, I always like to balance out the 'what I think you did wrong' with at least one other 'what I think you did right' and point out something(s) that I liked. It really helps on the receiver's end - makes it feel more like an investment and less like a personal attack.
From the perspective of other stuff...
Depends. Product feedback is slanted towards the extreme ends of the bell curve, and usually tilted towards negative - people only come back and review if they have emotional investment. My trust of reviews has little to do with positivity or negativity - it's quantity (how many reviews are bringing up the same experience or problem), quality (a detailed and thoughtful review is worth more than a brief or poorly written one), and veracity (you can usually spot paid shills from people who genuinely liked the product.)
