Once you realize that you can always make a new piece of art, critiques aren't bad at all. If you want to improve, they are imperative. I had a critique from my AD this summer, and once I fixed it, it was obvious. Thank goodness she saw what I couldn't. I also realized when working for someone else, I feel not at all bad about critiques or starting over. They are literally paying me for my time and my skill and to listen to them and make whatever changes they want. Working on something that isn't yours is pretty freeing, honestly.
You still need to keep that mindset when working on your own work. As a creator, you can create again. Everything is changeable. Nothing is precious. Sometimes you don't want to, but think back three years or even one; some work you loved is nothing compared to what you do now.
I did get a critique from a teacher on a thumbnail/sketch part of a book cover project, and he didn't get it. He said he didn't like it and I should redraw it. Now, I had spent a long time drawing this out the weekend before and was pretty done and ready to move on to the finish. I disagreed completely with him. I knew he couldn't see where I was going with it. So I ignored him, and finished it out how I wanted. And guess what, he loved it. When you accept a lot of critiques and give a lot of critiques, you can recognize when things are personal preference or just a not-good crit.
I always try to accept all crit that is offered or suggested, even/especially when I disagree. Sometimes I implement it and sometimes I ignore it, but I always try to think about why someone would comment on whatever it is. Why is it good? Why do I want to ignore it? Why do I feel strongly either way? If I ignore it, then I have to accept that I might fall on flat on my face and fail due to stubbornness.
Also, I can see and comment on what makes other people's work good but I'm self-blind. I'm so used to trying to constantly fix my work and not being attached to it too much, that critiques help me understand that I don't suck. It's like, 'oh, I'm doing something right too, not just only needing to improve'.
So yeah, I love critiques. Without them, I couldn't have possibly grown at all.