That does sound like an interesting adventure. Good thing he was able to get some sponsorship and donations, I think he said he spent about $100,000 on the trip?
Although having grown up near the Amazon, my first thought was "how in the world do you
walk down the Amazon?"
It's not like there is an access road or path that just follows the river all the way down - but I gather he meant he walked along roads that took him
near the river as often as he could.
There is a "highway" (often just a dirt/gravel road) that goes over the mountains and does cross some of the tributaries to the Amazon, but many places near the Amazon's source there are many steep waterfalls etc that he would not be able to just "walk" next to. And once reaching where the river gets larger and flatter, there is thick jungle all along the shore. I don't believe he could have literally
walked along there the whole way, not even in 2 years ! The yahoo article makes a point that there are other expeditions to travel the Amazon but which used boats, but he didn't? Iquitos is the largest city along the Amazon that is NOT linked to the outside world by road - everything has to come in by boat.
In my rebellious/adventurous teenage years I sometimes dreamed of running away and living off the land while paddling down the Amazon to the ocean, until I came to my senses and realized that 1) I don't speak Portuguese so would have trouble as soon as I crossed from Peru into Brazil and 2) what would happen after hitting the Atlantic ocean, it's not like I could paddle my dugout canoe all the way up the coast to the US!
Did you get a chance to read his blog? The yahoo article mentions that he kept one, but unfortunately the link that I think points to his blog gives me a "bandwidth exceeded" error, due to his sudden publicity I guess.
Oh well at least I have beer to drink. But really mad props to that guy.