'Groundbreaking' -U.S. editor on Prince Harry's new memoir

STORY: "We've seen other books come out in the past... but nothing quite like this. The scale of this and the intimate details he shares about life within the royal family there. We haven't seen anything like this before," Hill said.

The prince is on the cover of the U.S. publication's latest issue and inside the issue, he shares why he felt it was important to speak now.

The memoir gives a personal account of events such as Harry's struggles dealing with the death of his mother, Princess Diana and his time in the military - when he said he killed 25 Taliban insurgents while serving in Afghanistan.

Hill said the book shines a light on the institutional problems the monarchy faces.