I think that being dissatisfied with your own body image is fine... Actually, it's rather normal. It's never unhealthy to not like your body if you're out of shape, etc, but it can go down a bad route depending on what you do with that. You can be either constructive or deconstructive with it.
But if people get you down about having an ugly facial structure or something that obviously is unchangeable (save for invasive surgery), then they're just being jerks. That's like if I were to rag on the lady down the street for not exercising as much as she should because she's been in a wheelchair for over a decade because of a medical condition. She swims when she can, but it's not like she can do much else about it.