Although I've read, and watched, plenty of prequels, part of me is always a little disappointed by them. I don't want to know what's gone before. I don't want to see the edges of the story filled in, to see what was happening to those characters when the camera was following this character. I want to move forward, to get the answer to And then?
In a similar vein, I dislike it when authors give spoilers for their own works. Diana Wynne Jones, dearly though I love her work, does that way too often. She'll have a first-person narrator who's supposedly writing this book after the fact, and keeps sprinkling in tidbits about how things turn out. Stop that! I don't want to know how it ends until it ends! Oddly, though, flashbacks within a text don't bother me, as long as it's not "three-fourths of the book is one long flashback".
Anyway, I'm curious now: how many other people feel the same way? When you've got a character you like, are you as happy to see a prequel as a sequel? Or do you prefer one over the other? What about the foreshadowing-by-sledgehammer that some authors like? How much do spoilers spoil it for you?