I don't agree... I've DONE this journey, and I blogged about it daily.... after the first half, you kind of run out of things to write (hey guys, still on the bike. Yep, still cycling. etc etc)
But I also disagree because, even though he was still less than half way round when I was over halfway through the book, the pace of writing didn't change and the intrigue was still there. There was plenty of detail in the last part of the book, and the telling of what he did and where he went are very balanced throughout.
But maybe I'm biased :)