Nancy was my favorite name when I was about twelve years old, but I outgrew that.
It's one name that is very terminally dated. Well, not terminally, since some day, when everyone now alive is dead, it may well be seen as charmingly old-fashioned, and may even become popular again. But for now, very dated.
It also makes me think of Nancy Reagan, whom I despise.
But is it useable? Yes, very. It's not a name that will give its bearer a problem, or invite ridicule, so it's useable.