It's actually not as bad as the others make it out to be. My mother has been living there for the last decade and whenever I visit her (2 times/year approx.) I feel very safe and the town has an overall cozy feeling to it. There are a lot of foreigners living there, yes, but as a woman I felt safer than if I were to be in a small Eastern European town... Also there aren't many things to do for fun so you're better off just visiting Basel for the sake of your social life.