I just bought a pair of the Merrel Pace Glove's. I LOVE them!
I've slowly been building up the length of time I wear them and I can definitely feel the muscles in my feet getting worked. My feet haven't gotten that good a workout since I was doing several hrs of hatha/Iyengar yoga everday a couple years ago (need to start that habit up again...).
I freaking love Merrell shoes. My last shoes were the Siren Sport crosstrainers. I go a lot of miles and the soles of traditional shoes get really distorted/worn/just done for really quickly and then start hurting my feet really badly because I can't afford to buy new pairs that often. Should be interesting to see if the pace glove sole's wear as slowly as the dude at REI says they do...
I think VFF's are about the ugliest things ever invented. JMO.