now that we've all seen post of whether Fi users are comfortable talking about Fi, let's actually talk about it =)
first I'd like to clear up what I feel to be a number of misconceptions about Fi
1) selfish: Fi users are not selfish, we just have a tendency to solve our own problems first before helping others. The analogy I use most of the time is like planting your seeds before you give away your harvest
2) lazy: many FP types are hard workers, but we would rather work at a slower pace than more intense types like ENTJs and such.
3) irrational: most FPs I know can be rational if they need to. people mistake Fi for making decisions based one's emotions, but it isn't that at all. the difference is, FPs don't feel the need to empirically prove things the way TPs and TJs do. I can't really speak for SFPs, but I know for NFPs, Fi is content to say "I get it, now let's do it" or "I don't get it, let's wait a little while and get a good understanding first"