I have read both Through Sand and Snow and On Roads That Echo. To undertake such an epic journey, to cover 43,000 miles by bike, but also on horseback, foot and dugout canoe, through inhospitable terrain, takes determination and tenacity.
Charlie Walker's 4 year global travels are conveyed in his books with clarity, honesty and unflinching detail of the many highs and lows, physically and emotionally.
I would definitely recommend On Roads That Echo, but read Through Sand and Snow first. An unfathomable adventure, an incredible journey. Chapeau Charlie.