This thread's getting a little wobbly, but here's my two cents about Fe/Fi anyway.
I agree with a lot of what [MENTION=7111]fidelia[/MENTION] is saying. But I also am becoming more and more convinced that I'm a little skewed by growing up in a household that's much more Fi than Fe. For instance, when I'm trying to comfort someone, I'll ask them questions, but I also will often start talking about myself and how I've felt what they are feeling to try to affirm them. It was surprising to me when I came on this site to realize that a lot of Fe-users find this weird. There are other little things too that I don't know how to describe. I think this is my Fe anyway, though, adapting to the emotional situation at hand (growing up in an Fi-environment).
But one thing that it took me awhile to realize is that when Fi-users say things like "I like that/I don't like that," it's not just some random whim feeling that they're expressing, but it's a judgment about how they see the world based on a complex system.
I agree with all the Fe-users so far who've said that their feelings are less used to judge things than an Fi-users' are. I see my feelings as just one piece of information but not at all the main source of my information. A lot of times I feel like emotions can be divided into "pain/bad" and "pleasure/good." So my goal is to have as much good emotions and as little bad emotions as I can. This is how I try to regulate my emotions. I also try to help other people out with this too by trying to help them eliminate their bad emotions. I've had to learn that some people (Fi-users) don't appreciate this because they see even bad emotions as having a value. But this is how I come at things initially.
About when others are in pain and whether or not it's authentic if you try to sympathize with them even if you don't see how they're in pain, I see this as having different definitions of authenticity. Fi-users feel that it's authentic to only tell someone you feel sorry for them if you can see why they're upset. For Fe-users, it's more like if you show compassion for them being upset even if you can't see why they are, you're being authentic in your concern for them. To me, if I tell someone I'm sorry they're in pain and try to help them with it, but I don't understand it, it's like saying to them, "I genuinely care about you, and that's why I'm here for you in sympathizing."
I could say more, but I'll see how this thread continues.