By real-world standards? No. But that's less because of something wrong with her and more because of what a traumatic place the IZ version of earth would be to grow up. She gives the impression of a normal person who got trapped in the zim world, realized there was no way out, and as a result is super irritated all the time and uses vidya as a coping mechanism, which now that I think of it could make for an interesting theory. By the standards of the zim world she doesn't have much hope either, since the closest thing to well-adjusted there is being too brain dead to realize what an awful world it is. I like to imagine that maybe Dib will come around when he's older to start being more like gaz, and they'll both know that even if the world is awful, at least they're in it together.