My opinion is that if a gadget is safe and you're excited about it enough that it encourages you to work out, GO FOR IT!!! You may have seen my post about the Body by Jake Bun & Thigh Rocker...some people think this is a waste of money, but I like it, and it makes me look forward to my leg workouts.
As to whether is would be effective? It forces you to walk with your arms bent, which I always encourage anyway, belt or no belt. Walking with your arms bent helps you to engage your abs, and I've long said that walking can be a great ab workout, more so than running because you don't use your arms as much in running.
I guess there must be resistance in the powercords, and it looks like it would be evenly distributed. This would be better than using hand weights. They say on the Walker's Warehouse site that studies show it kicks up your workout a few notches.
If you've got the bread and you want to get it, do it, but be sure and report back to us!!!