The older versions are cooler; the one prior to this had a tank-tread style layout, and the one prior to that one was a car-style. What made both of the older ones "better", IMHO - was the fact that they included small monocle-style HMDs, manufactured (well, the internals, at least) by Kopin:
http://www.machinegrid.com/2009/02/taking-apart-the-atv-360-eyepiece-head-mounted-display/
A few months back I picked up the "car-style" version from ebay fairly cheap; it was pretty fun to drive around the house scaring the dog... ;D