"[G]ripping ... uplifting."
- The Wall Street Journal,
"This encapsulating narrative pinpoints human spirit and the limitations of the human body in the world of thrilling adventure."
- Adventure Travel,
"... his tales are thoughtful and insightful... A thoroughly enjoyable and readable book which manages to provide food for thought as well as a healthy dose of vicarious adrenalin."
- The Scottish Mountaineer,
"<em>Limits of the Known</em> takes the reader on magnificent journeys with some of the greatest explorers of their generations. The book is meticulously researched and skilfully written."
- Climber,
"What will almost certainly be the last of Roberts's many books is powerful and honest testimony to a life rich in both action and self-examination."
- Times Literary Supplement,