To be fair, as Doop says, the motivation behind those actions was to try and save the mutant race. She couldn't give a rats ass about humanity certainly,
She actively tried to wipe them out, that goes beyond "doesn't agree with their outlook" IMHO.
but she's definitely more in the terrorist/freedom fighter mold than just some random psychotic who runs around killing people for no reason. She has a cause.
Or an excuse, depending on how you look at it.
What's interesting about Mystique is that, like Magneto, it's possible to sympathize with her motivations, if not her methods. I personally find that makes villains much more compelling than someone who just kills for the sake of killing.
Up to a point yes, indeed, I thought probably the best line of the X2 movie was her reply to Nightcrawler when he asked why she didn't just use her powers to pass as human all the time; "Because I shouldn't have to". She's absolutely right, but that doesn't excuse her casually murdering people.
Anyway, she's more sociopathic than psychopathic, in my opinion.
Perhaps, though I'm not sure that makes her any less of a monster.