I don't like it for a boy. I like it for a girl. I know, I know, it's a surname-on-a-girl and I should hate it! But ever since I read that one of Zachary Taylor's daughters, who married Jefferson Davis and then died shortly after their marriage at a very young age, was named Sarah Knox but always called Knox, it somehow has a sweet nineteenth century flavor for me.
So yeah, I like it for a girl. But not for a boy.