I'm gonna have to fix that chin later.
I hear you should usually wait a while after finishing something before you declare it "finished." It's because of this kind of blindness. Sometimes, when you work on something for a while, you can start to miss things that would normally be obvious. Put it down for a few hours (or until the next day) and suddenly all the flaws jump out at you.
Of course, it's just a practice picture, so I'm not going to get too worked up about it, but things are really jumping out at me now.