Reebok Easytones?

Update:
I went to my local athletic shoe store, where the salespeople really know their stuff. I asked about these Reeboks and similar shoes put out by other companies. The guy said that the reason these shoes provide a workout is because the surface that comes in contact with the ground is built unstable on purpose, so you have to work a bit harder to maintain your balance. He said that he's heard of a few people suing the shoe manufacturers because they've broken their ankles and legs from losing their balance on the shoe. I decided against buying them because on some days, I'm accident-prone as it is and I don't really want to be trying to keep from tipping over when inserting an IV, running a code, etc. I'm kind of bummed out!