It's certainly a very unusual design. I could imagine horizontal scrolling working, but I think having both horizontal and vertical scrolling is a bad idea - it's too easy to get lost, and I feel like I want to zoom out to get a full overview of the site. It also makes it tricky to use the site with your hand on the mouse, because the scroll wheel only moves you up and down (the arrow buttons at the top are clickable, but I don't want to have to move the mouse up there to move sideways).
Thomas