Sometimes I'm bothered by the "last name used as a first name" thing, but this one doesn't strike me as a problem.
In fact, I sort of have a happy memory associated with this name. When I was in the hospital having my DD, the woman in the room with me on the 2nd day was having her fourth child. She had 2 boys and one girl already at home, and the little girl (who was 5) was hoping for a sister. I remember this other mom on the phone with her DD, breaking the news to her that the baby was a boy.
"I know you wanted a sister, but you and I will have lots of fun playing with baby Walker. You'll help me take care of him, right?"
It was SO cute, and I've always had a soft spot in my heart for the name Walker since that day. Somewhere today, that Walker is 12 and his older sister is 17 now -- wow!