You've gotta love companies who go out on a limb and try to do something different with a product that is pretty well designed already. The mouse, for example, is already doing pretty well. It's got a couple buttons, a scrollwheel — what more do you need?
Apparently Buffalo thinks you need a directional pad in place of the scrollwheel for some reason. I guess if you're constantly needing to scroll horizontally this could come in handy, but I can't think of too many applications where that would be an issue. Maybe gaming? Nah, not really. Well, kudos for trying something new, Buffalo.