As a female
Shannon it's a bit difficult for me to judge this name objectively because I love my name on me, but I would never use it in naming ANYTHING else. That being said, I think that
Shannon is lovely on a boy or a girl, and I like it more and more as a boy's name as I get older. It definitely is an androgynous name, whose look or sound is pretty neutral and not typically categorized as either "masculine" or "feminine" sounding.
I think
Shannon makes a beautiful middle name, too, actually. There are some pretty cool combinations with
Shannon as a middle name, it's pretty unusual to see the name used in that position.