A number of IRA victims are affronted that a figure so closely associated with IRA violence could become Ireland's head of state.
One is Ann Travers, a Catholic, whose sister was killed and whose magistrate father was badly injured in an IRA shooting in Belfast 25 years ago. Mrs Travers now lives south of the border.
"When I first heard it I was horrified, then I felt really angry," she said, adding that Mr McGuinness's mentions of Nelson Mandela "made me want to scream."
But Alan McBride, a Protestant from Belfast, offers a different perspective.
He lost his wife Sharon, and his father-in-law in what became known as the Shankill bombing. "I can understand how people who have been hurt and have had people murdered by the IRA, would be feeling," he said.
"But so many amazing things have happened, like Martin McGuinness and Ian Paisley sharing power. Maybe it's just a sign of the times and how far he has come, and how far we have come."