"Author's narration undermines this production"
As a travelogue, this is entertaining enough, although I agree with other reviewers that it's also not especially insightful. It's often just a straight-up narrative of what happened, interspersed with (sometimes badly researched) history. It's the latter that really undermines the work. I can't speak for his grasp of Russian history, but his account of the Mongols is at least fifty years out of date and terribly bigoted. It's too bad, because the trip he takes is really epic, and he clearly had a lot of guts and a sense of adventure to take it on at all.
He's also not the greatest narrator of his own writing; the book would certainly have benefited from a professional reader who would have given it a greater sense of adventure through his/her delivery. The author undercuts his own authority because he hasn't bothered to find out how to pronounce names like "Genghis Khan" and "Ranulf Fiennes." The former comes up a lot, and it makes him sound particularly ignorant. At one point he quotes from a historical source which evidently uses the more modern (and more phonetic) spelling "Chinggis Khan." But at the end of the quote, the author returns to his own mispronunciation of the name, apparently not having noticed the difference.