Great characters inspire me. I love to read a story that involves well rounded, intriguing and complex characters. If I can empathize with the character - and not in a Mary Sue sort of way - it's even better. Plot is secondary to me. I enjoy seeing a character dropped into the middle of a situation, then seeing how they react to events. I can accept almost any crap plot if I'm invested in the people on the page. In my opinion, the worst thing you can do is hand me an intriguing plot and a flat character who will behave exactly as expected. I'll stick around until the end to see what happens, but I won't be happy about it.
(Why would you read a book that you don't like? you ask. I'm just one of those people. You know those people; the ones who bitch and moan about how terrible the book is the entire time they're reading it, and then continue to bitch and moan about it months later. If it's a library book I might quit once I realize what I'm in for, but if I paid for the book, I'm in it to the bitter end.)
Great characters are something I want to excel at in my own writing. I find myself getting lost in the back stories, personalities and emotions of the people who live in my head (not in the creepy sort of way). Nothing is more satisfying to me than to write about a character observing, interacting with, and responding to his or her world.
How do you feel about characters?